diff --git a/athena/activity/public/activity.h b/athena/activity/public/activity.h
index 74a6c4112361..041449b6721c 100644
--- a/athena/activity/public/activity.h
+++ b/athena/activity/public/activity.h
@@ -9,6 +9,10 @@
 
 #include "athena/athena_export.h"
 
+namespace aura {
+class Window;
+}
+
 namespace athena {
 
 class ActivityViewModel;
@@ -72,6 +76,10 @@ class ATHENA_EXPORT Activity {
 
   // Returns the current media state.
   virtual ActivityMediaState GetMediaState() = 0;
+
+  // Returns the window for the activity. This can be used to determine the
+  // stacking order of this activity against others.
+  virtual aura::Window* GetWindow() = 0;
 };
 
 }  // namespace athena
diff --git a/athena/athena.gyp b/athena/athena.gyp
index 448ba4e30594..6335641564b1 100644
--- a/athena/athena.gyp
+++ b/athena/athena.gyp
@@ -115,22 +115,39 @@
         'ATHENA_IMPLEMENTATION',
       ],
       'sources': [
+        'content/app_activity.cc',
+        'content/app_activity.h',
+        'content/app_activity_proxy.cc',
+        'content/app_activity_proxy.h',
+        'content/app_activity_registry.cc',
+        'content/app_activity_registry.h',
+        'content/app_registry_impl.cc',
+        'content/content_activity_factory.cc',
+        'content/content_app_model_builder.cc',
+        'content/public/app_registry.h',
         'content/public/content_activity_factory.h',
         'content/public/content_app_model_builder.h',
         'content/public/web_contents_view_delegate_creator.h',
-        'content/content_activity_factory.cc',
-        'content/content_app_model_builder.cc',
-        'content/app_activity.h',
-        'content/app_activity.cc',
         'content/render_view_context_menu_impl.cc',
         'content/render_view_context_menu_impl.h',
-        'content/web_activity.h',
         'content/web_activity.cc',
+        'content/web_activity.h',
         'content/web_contents_view_delegate_factory_impl.cc',
         'virtual_keyboard/public/virtual_keyboard_manager.h',
         'virtual_keyboard/virtual_keyboard_manager_impl.cc',
       ],
     },
+    {
+      'target_name': 'athena_content_support_lib',
+      'type': 'static_library',
+      'dependencies': [
+        '../content/content.gyp:content_browser',
+      ],
+      'sources': [
+        'content/delegate/app_content_control_delegate_impl.cc',        
+        'content/public/app_content_control_delegate.h',
+      ],
+    },
     {
       'target_name': 'athena_test_support',
       'type': 'static_library',
@@ -152,6 +169,7 @@
         'resources/athena_resources.gyp:athena_resources',
       ],
       'sources': [
+        'content/public/app_content_control_delegate.h',
         'test/athena_test_base.cc',
         'test/athena_test_base.h',
         'test/athena_test_helper.cc',
@@ -160,6 +178,7 @@
         'test/sample_activity.h',
         'test/sample_activity_factory.cc',
         'test/sample_activity_factory.h',
+        'test/test_app_content_control_delegate_impl.cc',
         'test/test_app_model_builder.cc',
         'test/test_app_model_builder.h',
         'test/test_screen_manager_delegate.cc',
@@ -178,11 +197,12 @@
         'resources/athena_resources.gyp:athena_pak',
       ],
       'sources': [
-        'test/athena_unittests.cc',
         'activity/activity_manager_unittest.cc',
+        'content/app_activity_unittest.cc',
         'home/home_card_unittest.cc',
         'input/accelerator_manager_unittest.cc',
         'screen/screen_manager_unittest.cc',
+        'test/athena_unittests.cc',
         'wm/split_view_controller_unittest.cc',
         'wm/window_list_provider_impl_unittest.cc',
         'wm/window_manager_unittest.cc',
diff --git a/athena/content/OWNERS b/athena/content/OWNERS
new file mode 100644
index 000000000000..b03b46b0118b
--- /dev/null
+++ b/athena/content/OWNERS
@@ -0,0 +1,4 @@
+skuhne@chromium.org
+oshima@chromium.org
+mukai@chromium.org
+
diff --git a/athena/content/app_activity.cc b/athena/content/app_activity.cc
index c90daffa625e..309454ab401e 100644
--- a/athena/content/app_activity.cc
+++ b/athena/content/app_activity.cc
@@ -5,9 +5,13 @@
 #include "athena/content/app_activity.h"
 
 #include "athena/activity/public/activity_manager.h"
+#include "athena/content/app_activity_registry.h"
+#include "athena/content/public/app_content_control_delegate.h"
+#include "athena/content/public/app_registry.h"
 #include "content/public/browser/web_contents.h"
 #include "extensions/shell/browser/shell_app_window.h"
 #include "ui/views/controls/webview/webview.h"
+#include "ui/views/widget/widget.h"
 
 namespace athena {
 
@@ -15,13 +19,14 @@ namespace athena {
 AppActivity::AppActivity(extensions::ShellAppWindow* app_window)
     : app_window_(app_window),
       web_view_(NULL),
-      current_state_(ACTIVITY_UNLOADED) {
-  DCHECK(app_window_);
+      current_state_(ACTIVITY_UNLOADED),
+      app_activity_registry_(NULL) {
 }
 
 AppActivity::~AppActivity() {
-  if (GetCurrentState() != ACTIVITY_UNLOADED)
-    SetCurrentState(ACTIVITY_UNLOADED);
+  // If this activity is registered, we unregister it now.
+  if (app_activity_registry_)
+    app_activity_registry_->UnregisterAppActivity(this);
 }
 
 ActivityViewModel* AppActivity::GetActivityViewModel() {
@@ -29,35 +34,41 @@ ActivityViewModel* AppActivity::GetActivityViewModel() {
 }
 
 void AppActivity::SetCurrentState(Activity::ActivityState state) {
+  ActivityState current_state = state;
+  // Remember the last requested state now so that a call to GetCurrentState()
+  // returns the new state.
+  current_state_ = state;
+
   switch (state) {
     case ACTIVITY_VISIBLE:
       // Fall through (for the moment).
     case ACTIVITY_INVISIBLE:
       // By clearing the overview mode image we allow the content to be shown.
       overview_mode_image_ = gfx::ImageSkia();
-      // TODO(skuhne): Find out how to reload an app from the extension system.
+      // Note: A reload from the unloaded state will be performed through the
+      // |AppActivityProxy| object and no further action isn't necessary here.
       break;
     case ACTIVITY_BACKGROUND_LOW_PRIORITY:
-      DCHECK(ACTIVITY_VISIBLE == current_state_ ||
-             ACTIVITY_INVISIBLE == current_state_);
+      DCHECK(ACTIVITY_VISIBLE == current_state ||
+             ACTIVITY_INVISIBLE == current_state);
       // TODO(skuhne): Do this.
       break;
     case ACTIVITY_PERSISTENT:
-      DCHECK_EQ(ACTIVITY_BACKGROUND_LOW_PRIORITY, current_state_);
+      DCHECK_EQ(ACTIVITY_BACKGROUND_LOW_PRIORITY, current_state);
       // TODO(skuhne): Do this.
       break;
     case ACTIVITY_UNLOADED:
-      DCHECK_NE(ACTIVITY_UNLOADED, current_state_);
-      // TODO(skuhne): Find out how to evict an app from the extension system.
-      //      web_view_->EvictContent();
+      DCHECK_NE(ACTIVITY_UNLOADED, current_state);
+      // This will cause the application to shut down, close its windows and
+      // delete this object. Instead a |AppActivityProxy| will be created as
+      // place holder.
+      if (app_activity_registry_)
+        app_activity_registry_->Unload();
       break;
   }
-  // Remember the last requested state.
-  current_state_ = state;
 }
 
 Activity::ActivityState AppActivity::GetCurrentState() {
-  // TODO(skuhne): Check here also eviction status.
   if (!web_view_) {
     DCHECK_EQ(ACTIVITY_UNLOADED, current_state_);
     return ACTIVITY_UNLOADED;
@@ -82,6 +93,10 @@ Activity::ActivityMediaState AppActivity::GetMediaState() {
   return Activity::ACTIVITY_MEDIA_STATE_NONE;
 }
 
+aura::Window* AppActivity::GetWindow() {
+  return !web_view_ ? NULL : web_view_->GetWidget()->GetNativeWindow();
+}
+
 void AppActivity::Init() {
 }
 
@@ -130,4 +145,26 @@ void AppActivity::DidUpdateFaviconURL(
   ActivityManager::Get()->UpdateActivity(this);
 }
 
+void AppActivity::DidStartNavigationToPendingEntry(
+      const GURL& url,
+      content::NavigationController::ReloadType reload_type) {
+  if (!app_activity_registry_)
+    RegisterActivity();
+}
+
+// Register an |activity| with an application.
+// Note: This should only get called once for an |app_window| of the
+// |activity|.
+void AppActivity::RegisterActivity() {
+  content::WebContents* web_contents = app_window_->GetAssociatedWebContents();
+  AppRegistry* app_registry = AppRegistry::Get();
+  // Get the application's registry.
+  app_activity_registry_ = app_registry->GetAppActivityRegistry(
+          app_registry->GetDelegate()->GetApplicationID(web_contents),
+          web_contents->GetBrowserContext());
+  DCHECK(app_activity_registry_);
+  // Register the activity.
+  app_activity_registry_->RegisterAppActivity(this);
+}
+
 }  // namespace athena
diff --git a/athena/content/app_activity.h b/athena/content/app_activity.h
index 4f6ef2b3d47a..105f7285bfc7 100644
--- a/athena/content/app_activity.h
+++ b/athena/content/app_activity.h
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef ATHENA_CONTENT_PUBLIC_APP_ACTIVITY_H_
-#define ATHENA_CONTENT_PUBLIC_APP_ACTIVITY_H_
+#ifndef ATHENA_CONTENT_APP_ACTIVITY_H_
+#define ATHENA_CONTENT_APP_ACTIVITY_H_
 
 #include "athena/activity/public/activity.h"
 #include "athena/activity/public/activity_view_model.h"
@@ -20,6 +20,9 @@ class WebView;
 
 namespace athena {
 
+class AppActivityRegistry;
+
+// The activity object for a hosted V2 application.
 class AppActivity : public Activity,
                     public ActivityViewModel,
                     public content::WebContentsObserver {
@@ -27,13 +30,13 @@ class AppActivity : public Activity,
   explicit AppActivity(extensions::ShellAppWindow* app_window);
   virtual ~AppActivity();
 
- protected:
   // Activity:
   virtual athena::ActivityViewModel* GetActivityViewModel() OVERRIDE;
   virtual void SetCurrentState(Activity::ActivityState state) OVERRIDE;
   virtual ActivityState GetCurrentState() OVERRIDE;
   virtual bool IsVisible() OVERRIDE;
   virtual ActivityMediaState GetMediaState() OVERRIDE;
+  virtual aura::Window* GetWindow() OVERRIDE;
 
   // ActivityViewModel:
   virtual void Init() OVERRIDE;
@@ -44,13 +47,20 @@ class AppActivity : public Activity,
   virtual void CreateOverviewModeImage() OVERRIDE;
   virtual gfx::ImageSkia GetOverviewModeImage() OVERRIDE;
 
+ protected:
   // content::WebContentsObserver:
   virtual void TitleWasSet(content::NavigationEntry* entry,
                            bool explicit_set) OVERRIDE;
   virtual void DidUpdateFaviconURL(
       const std::vector<content::FaviconURL>& candidates) OVERRIDE;
+  virtual void DidStartNavigationToPendingEntry(
+        const GURL& url,
+        content::NavigationController::ReloadType reload_type) OVERRIDE;
 
  private:
+  // Register this activity with its application.
+  void RegisterActivity();
+
   scoped_ptr<extensions::ShellAppWindow> app_window_;
   views::WebView* web_view_;
 
@@ -60,6 +70,11 @@ class AppActivity : public Activity,
   // The image which will be used in overview mode.
   gfx::ImageSkia overview_mode_image_;
 
+  // If known the registry which holds all activities for the associated app.
+  // This object is owned by |AppRegistry| and will be a valid pointer as long
+  // as this object lives.
+  AppActivityRegistry* app_activity_registry_;
+
   DISALLOW_COPY_AND_ASSIGN(AppActivity);
 };
 
diff --git a/athena/content/app_activity_proxy.cc b/athena/content/app_activity_proxy.cc
new file mode 100644
index 000000000000..222e697b38ba
--- /dev/null
+++ b/athena/content/app_activity_proxy.cc
@@ -0,0 +1,84 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "athena/content/app_activity_proxy.h"
+
+#include "athena/content/app_activity_registry.h"
+#include "ui/views/view.h"
+#include "ui/views/widget/widget.h"
+
+namespace athena {
+
+AppActivityProxy::AppActivityProxy(ActivityViewModel* view_model,
+                                   AppActivityRegistry* creator) :
+    app_activity_registry_(creator),
+    title_(view_model->GetTitle()),
+    image_(view_model->GetOverviewModeImage()),
+    color_(view_model->GetRepresentativeColor()),
+    // TODO(skuhne): We probably need to do something better with the view
+    // (e.g. showing the image).
+    view_(new views::View()) {}
+
+AppActivityProxy::~AppActivityProxy() {
+  app_activity_registry_->ProxyDestroyed(this);
+}
+
+ActivityViewModel* AppActivityProxy::GetActivityViewModel() {
+  return this;
+}
+
+void AppActivityProxy::SetCurrentState(ActivityState state) {
+  // We ignore all calls which try to re-load the application at a lower than
+  // running invisible state.
+  if (state != ACTIVITY_VISIBLE && state != ACTIVITY_INVISIBLE)
+    return;
+  app_activity_registry_->RestartApplication(this);
+  // Note: This object is now destroyed.
+}
+
+Activity::ActivityState AppActivityProxy::GetCurrentState() {
+  return ACTIVITY_UNLOADED;
+}
+
+bool AppActivityProxy::IsVisible() {
+  return true;
+}
+
+Activity::ActivityMediaState AppActivityProxy::GetMediaState() {
+  // This proxy has never any media playing.
+  return ACTIVITY_MEDIA_STATE_NONE;
+}
+
+aura::Window* AppActivityProxy::GetWindow() {
+  return view_->GetWidget()->GetNativeWindow();
+}
+
+void AppActivityProxy::Init() {
+}
+
+SkColor AppActivityProxy::GetRepresentativeColor() const {
+  return color_;
+}
+
+base::string16 AppActivityProxy::GetTitle() const {
+  return title_;
+}
+
+bool AppActivityProxy::UsesFrame() const {
+  return true;
+}
+
+views::View* AppActivityProxy::GetContentsView() {
+  return view_;
+}
+
+void AppActivityProxy::CreateOverviewModeImage() {
+  // Nothing we can do here.
+}
+
+gfx::ImageSkia AppActivityProxy::GetOverviewModeImage() {
+  return image_;
+}
+
+}  // namespace athena
diff --git a/athena/content/app_activity_proxy.h b/athena/content/app_activity_proxy.h
new file mode 100644
index 000000000000..c5092e865129
--- /dev/null
+++ b/athena/content/app_activity_proxy.h
@@ -0,0 +1,63 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef ATHENA_CONTENT_APP_ACTIVITY_PROXY_H_
+#define ATHENA_CONTENT_APP_ACTIVITY_PROXY_H_
+
+#include <vector>
+
+#include "athena/activity/public/activity.h"
+#include "athena/activity/public/activity_view_model.h"
+#include "athena/content/app_activity_proxy.h"
+#include "ui/gfx/image/image_skia.h"
+
+namespace athena {
+
+class AppActivityRegistry;
+
+// This activity object is a proxy placeholder for the application while it is
+// unloaded. When selected it will launch the applciation again and destroy
+// itself indirectly.
+class AppActivityProxy : public Activity,
+                         public ActivityViewModel {
+ public:
+  AppActivityProxy(ActivityViewModel* view_model, AppActivityRegistry* creator);
+  virtual ~AppActivityProxy();
+
+  // Activity overrides:
+  virtual ActivityViewModel* GetActivityViewModel() OVERRIDE;
+  virtual void SetCurrentState(ActivityState state) OVERRIDE;
+  virtual ActivityState GetCurrentState() OVERRIDE;
+  virtual bool IsVisible() OVERRIDE;
+  virtual ActivityMediaState GetMediaState() OVERRIDE;
+  virtual aura::Window* GetWindow() OVERRIDE;
+
+  // ActivityViewModel overrides:
+  virtual void Init() OVERRIDE;
+  virtual SkColor GetRepresentativeColor() const OVERRIDE;
+  virtual base::string16 GetTitle() const OVERRIDE;
+  virtual bool UsesFrame() const OVERRIDE;
+  virtual views::View* GetContentsView() OVERRIDE;
+  virtual void CreateOverviewModeImage() OVERRIDE;
+  virtual gfx::ImageSkia GetOverviewModeImage() OVERRIDE;
+
+ private:
+  // The creator of this object which needs to be informed if the object gets
+  // destroyed or the application should get restarted.
+  AppActivityRegistry* app_activity_registry_;
+
+  // The presentation values.
+  const base::string16 title_;
+  const gfx::ImageSkia image_;
+  const SkColor color_;
+
+  // The associated view.
+  views::View* view_;
+
+  DISALLOW_COPY_AND_ASSIGN(AppActivityProxy);
+};
+
+}  // namespace athena
+
+#endif  // ATHENA_CONTENT_APP_ACTIVITY_PROXY_H_
diff --git a/athena/content/app_activity_registry.cc b/athena/content/app_activity_registry.cc
new file mode 100644
index 000000000000..dc7bce9c75cc
--- /dev/null
+++ b/athena/content/app_activity_registry.cc
@@ -0,0 +1,146 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "athena/content/app_activity_registry.h"
+
+#include "athena/activity/public/activity_manager.h"
+#include "athena/content/app_activity.h"
+#include "athena/content/app_activity_proxy.h"
+#include "athena/content/public/app_content_control_delegate.h"
+#include "athena/content/public/app_registry.h"
+#include "ui/aura/window.h"
+#include "ui/views/view.h"
+#include "ui/views/widget/widget.h"
+
+namespace athena {
+
+AppActivityRegistry::AppActivityRegistry(
+    const std::string& app_id,
+    content::BrowserContext* browser_context) :
+      app_id_(app_id),
+      browser_context_(browser_context),
+      unloaded_activity_proxy_(NULL) {}
+
+AppActivityRegistry::~AppActivityRegistry() {
+  CHECK(activity_list_.empty());
+  if (unloaded_activity_proxy_)
+    ActivityManager::Get()->RemoveActivity(unloaded_activity_proxy_);
+  DCHECK(!unloaded_activity_proxy_);
+}
+
+void AppActivityRegistry::RegisterAppActivity(AppActivity* app_activity) {
+  if (unloaded_activity_proxy_) {
+    // Since we add an application window, the activity isn't unloaded anymore.
+    ActivityManager::Get()->RemoveActivity(unloaded_activity_proxy_);
+    // With the removal the object should have been deleted and we should have
+    // been informed of the object's destruction.
+    DCHECK(!unloaded_activity_proxy_);
+  }
+  // The same window should never be added twice.
+  CHECK(std::find(activity_list_.begin(),
+                  activity_list_.end(),
+                  app_activity) == activity_list_.end());
+  activity_list_.push_back(app_activity);
+}
+
+void AppActivityRegistry::UnregisterAppActivity(AppActivity* app_activity) {
+  // It is possible that a detach gets called without ever being attached.
+  std::vector<AppActivity*>::iterator it =
+      std::find(activity_list_.begin(), activity_list_.end(), app_activity);
+  if (it == activity_list_.end())
+    return;
+
+  activity_list_.erase(it);
+  // When the last window gets destroyed and there is no proxy to restart, we
+  // delete ourselves.
+  if (activity_list_.empty() && !unloaded_activity_proxy_) {
+    AppRegistry::Get()->RemoveAppActivityRegistry(this);
+    // after this call this object should be gone.
+  }
+}
+
+AppActivity* AppActivityRegistry::GetAppActivityAt(size_t index) {
+  if (index >= activity_list_.size())
+    return NULL;
+  return activity_list_[index];
+}
+
+void AppActivityRegistry::Unload() {
+  CHECK(!unloaded_activity_proxy_);
+  DCHECK(!activity_list_.empty());
+
+  // In order to allow an entire application to unload we require that all of
+  // its activities are marked as unloaded.
+  for (std::vector<AppActivity*>::iterator it = activity_list_.begin();
+       it != activity_list_.end(); ++it) {
+    if ((*it)->GetCurrentState() != Activity::ACTIVITY_UNLOADED)
+      return;
+  }
+
+  // Create an activity proxy which can be used to re-activate the app. Insert
+  // the proxy then into the activity stream at the location of the (newest)
+  // current activity.
+  unloaded_activity_proxy_ =
+      new AppActivityProxy(activity_list_[0]->GetActivityViewModel(), this);
+  ActivityManager::Get()->AddActivity(unloaded_activity_proxy_);
+  // The new activity should be in the place of the most recently used app
+  // window. To get it there, we get the most recently used application window
+  // and place the proxy activities window in front or behind, so that when the
+  // activity disappears it takes its place.
+  MoveBeforeMruApplicationWindow(unloaded_activity_proxy_->GetWindow());
+
+  // Unload the application. This operation will be asynchronous.
+  if (!AppRegistry::Get()->GetDelegate()->UnloadApplication(app_id_,
+                                                            browser_context_)) {
+    while(!activity_list_.empty())
+      delete activity_list_.back();
+  }
+}
+
+void AppActivityRegistry::ProxyDestroyed(AppActivityProxy* proxy) {
+  DCHECK_EQ(unloaded_activity_proxy_, proxy);
+  unloaded_activity_proxy_ = NULL;
+  if (activity_list_.empty()) {
+    AppRegistry::Get()->RemoveAppActivityRegistry(this);
+    // |This| is gone now.
+  }
+}
+
+void AppActivityRegistry::RestartApplication(AppActivityProxy* proxy) {
+  DCHECK_EQ(unloaded_activity_proxy_, proxy);
+  // Restart the application.
+  AppRegistry::Get()->GetDelegate()->RestartApplication(app_id_,
+                                                        browser_context_);
+  // Remove the activity from the Activity manager.
+  ActivityManager::Get()->RemoveActivity(unloaded_activity_proxy_);
+  delete unloaded_activity_proxy_;  // Will call ProxyDestroyed.
+  // After this call |this| might be gone if the app did not open a window yet.
+}
+
+void AppActivityRegistry::MoveBeforeMruApplicationWindow(aura::Window* window) {
+  DCHECK(activity_list_.size());
+  // TODO(skuhne): This needs to be changed to some kind of delegate which
+  // resides in the window manager.
+  const aura::Window::Windows children =
+      activity_list_[0]->GetWindow()->parent()->children();;
+  // Find the first window in the container which is part of the application.
+  for (aura::Window::Windows::const_iterator child_iterator = children.begin();
+      child_iterator != children.end(); ++child_iterator) {
+    for (std::vector<AppActivity*>::iterator app_iterator =
+             activity_list_.begin();
+         app_iterator != activity_list_.end(); ++app_iterator) {
+      if (*child_iterator == (*app_iterator)->GetWindow()) {
+        // Since "StackChildBelow" does not change the order if the window
+        // if the window is below - but not immediately behind - the target
+        // window, we re-stack both ways.
+        window->parent()->StackChildBelow(window, *child_iterator);
+        window->parent()->StackChildBelow(*child_iterator, window);
+        return;
+      }
+    }
+  }
+  NOTREACHED() << "The application does not get tracked by the mru list";
+}
+
+}  // namespace athena
diff --git a/athena/content/app_activity_registry.h b/athena/content/app_activity_registry.h
new file mode 100644
index 000000000000..14ef7de3945b
--- /dev/null
+++ b/athena/content/app_activity_registry.h
@@ -0,0 +1,103 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef ATHENA_CONTENT_APP_ACTIVITY_REGISTRY_H_
+#define ATHENA_CONTENT_APP_ACTIVITY_REGISTRY_H_
+
+#include <vector>
+
+#include "athena/activity/public/activity_view_model.h"
+#include "athena/content/app_activity_proxy.h"
+
+namespace aura {
+class Window;
+}
+
+namespace content {
+class BrowserContext;
+}
+
+namespace athena {
+
+class AppActivity;
+
+// This class keeps track of all existing |AppActivity|s and shuts down all of
+// them when the application gets unloaded to save memory. It will then replace
+// the |AppActivity| in the Activity list as proxy to allow restarting of the
+// application.
+class ATHENA_EXPORT AppActivityRegistry {
+ public:
+  AppActivityRegistry(const std::string& app_id,
+                      content::BrowserContext* browser_context);
+  virtual ~AppActivityRegistry();
+
+  // Register an |AppActivity| with this application.
+  void RegisterAppActivity(AppActivity* app_activity);
+
+  // Unregister a previously attached |AppActivity|.
+  // Note that detaching the last |AppActivity| will delete this object - unless
+  // the resource manager was trying to unload the application.
+  // Note furthermore that Detach can be called without ever being registered.
+  void UnregisterAppActivity(AppActivity* app_activity);
+
+  // Returns the number of activities/windows with this application.
+  int NumberOfActivities() const { return activity_list_.size(); }
+
+  // Returns the |AppActivity| at |index|. It will return NULL if an invalid
+  // index was specified.
+  AppActivity* GetAppActivityAt(size_t index);
+
+  // Unload all application associated activities to save resources.
+  void Unload();
+
+  // Returns true if the application is in the unloaded state.
+  bool IsUnloaded() { return unloaded_activity_proxy_ != NULL; }
+
+  content::BrowserContext* browser_context() const { return browser_context_; }
+  const std::string& app_id() const { return app_id_; }
+
+  AppActivityProxy* unloaded_activity_proxy_for_test() {
+    return unloaded_activity_proxy_;
+  }
+
+ protected:
+  friend AppActivityProxy;
+
+  // When the |AppActivityProxy| gets destroyed it should call this function
+  // to disconnect from this object. This call might destroy |this|.
+  void ProxyDestroyed(AppActivityProxy* proxy);
+
+  // When called by the |AppActivityProxy| to restart the application, it can
+  // cause the application to restart. When that happens the proxy will get
+  // destroyed. After this call |this| might be destroyed.
+  void RestartApplication(AppActivityProxy* proxy);
+
+ private:
+  // Move the window before the most recently used application window.
+  void MoveBeforeMruApplicationWindow(aura::Window* window);
+
+  // A list of all activities associated with this application.
+  std::vector<AppActivity*> activity_list_;
+
+  // The application id for this proxy.
+  std::string app_id_;
+
+  // The browser context of the user.
+  content::BrowserContext* browser_context_;
+
+  // When the activity is unloaded this is the AppActivityProxy. The object is
+  // owned the the ActivityManager.
+  AppActivityProxy* unloaded_activity_proxy_;
+
+  // The presentation values.
+  SkColor color_;
+  base::string16 title_;
+  gfx::ImageSkia image_;
+
+  DISALLOW_COPY_AND_ASSIGN(AppActivityRegistry);
+};
+
+}  // namespace athena
+
+#endif  // ATHENA_CONTENT_APP_ACTIVITY_REGISTRY_H_
diff --git a/athena/content/app_activity_unittest.cc b/athena/content/app_activity_unittest.cc
new file mode 100644
index 000000000000..f94cc85f1626
--- /dev/null
+++ b/athena/content/app_activity_unittest.cc
@@ -0,0 +1,412 @@
+/// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "athena/activity/public/activity_factory.h"
+#include "athena/activity/public/activity_manager.h"
+#include "athena/content/app_activity.h"
+#include "athena/content/app_activity_registry.h"
+#include "athena/content/public/app_content_control_delegate.h"
+#include "athena/content/public/app_registry.h"
+#include "athena/test/athena_test_base.h"
+#include "extensions/shell/browser/shell_app_window.h"
+#include "ui/aura/window.h"
+#include "ui/views/view.h"
+#include "ui/views/widget/widget.h"
+
+
+namespace content {
+class BrowserContext;
+}
+
+namespace athena {
+namespace test {
+
+namespace {
+
+// An identifier for the running apps.
+const char kDummyApp1[] = "aaaaaaa";
+const char kDummyApp2[] = "bbbbbbb";
+
+// A dummy test app activity which works without content / ShellAppWindow.
+class TestAppActivity : public AppActivity {
+ public:
+  explicit TestAppActivity(const std::string& app_id) :
+      AppActivity(NULL),
+      app_id_(app_id),
+      view_(new views::View()),
+      current_state_(ACTIVITY_VISIBLE) {
+    app_activity_registry_ =
+        AppRegistry::Get()->GetAppActivityRegistry(app_id, NULL);
+    app_activity_registry_->RegisterAppActivity(this);
+  }
+  virtual ~TestAppActivity() {
+    app_activity_registry_->UnregisterAppActivity(this);
+  }
+
+  AppActivityRegistry* app_activity_registry() {
+    return app_activity_registry_;
+  }
+
+  // Activity:
+  virtual ActivityViewModel* GetActivityViewModel() OVERRIDE {
+    return this;
+  }
+  virtual void SetCurrentState(Activity::ActivityState state) OVERRIDE {
+    current_state_ = state;
+  }
+  virtual ActivityState GetCurrentState() OVERRIDE {
+    return current_state_;
+  }
+  virtual bool IsVisible() OVERRIDE {
+    return true;
+  }
+  virtual ActivityMediaState GetMediaState() OVERRIDE {
+    return Activity::ACTIVITY_MEDIA_STATE_NONE;
+  }
+  virtual aura::Window* GetWindow() OVERRIDE {
+    return view_->GetWidget()->GetNativeWindow();
+  }
+
+  // ActivityViewModel:
+  virtual void Init() OVERRIDE {}
+  virtual SkColor GetRepresentativeColor() const OVERRIDE { return 0; }
+  virtual base::string16 GetTitle() const OVERRIDE { return title_; }
+  virtual bool UsesFrame() const OVERRIDE { return true; }
+  virtual views::View* GetContentsView() OVERRIDE { return view_; }
+  virtual void CreateOverviewModeImage() OVERRIDE {}
+
+ private:
+  // If known the registry which holds all activities for the associated app.
+  AppActivityRegistry* app_activity_registry_;
+
+  // The application ID.
+  const std::string& app_id_;
+
+  // The title of the activity.
+  base::string16 title_;
+
+  // Our view.
+  views::View* view_;
+
+  // The current state for this activity.
+  ActivityState current_state_;
+
+  DISALLOW_COPY_AND_ASSIGN(TestAppActivity);
+};
+
+// An AppContentDelegateClass which we can query for call stats.
+class TestAppContentControlDelegate : public AppContentControlDelegate {
+ public:
+  TestAppContentControlDelegate() : unload_called_(0),
+                                    restart_called_(0) {}
+  virtual ~TestAppContentControlDelegate() {}
+
+  int unload_called() { return unload_called_; }
+  int restart_called() { return restart_called_; }
+  void SetExtensionID(const std::string& extension_id) {
+    extension_id_to_return_ = extension_id;
+  }
+
+  // Unload an application. Returns true when unloaded.
+  virtual bool UnloadApplication(
+      const std::string& app_id,
+      content::BrowserContext* browser_context) OVERRIDE {
+    unload_called_++;
+    // Since we did not close anything we let the framework clean up.
+    return false;
+  }
+  // Restarts an application. Returns true when the restart was initiated.
+  virtual bool RestartApplication(
+      const std::string& app_id,
+      content::BrowserContext* browser_context) OVERRIDE {
+    restart_called_++;
+    return true;
+  }
+  // Returns the application ID (or an empty string) for a given web content.
+  virtual std::string GetApplicationID(
+      content::WebContents* web_contents) OVERRIDE {
+    return extension_id_to_return_;
+  }
+
+ private:
+  int unload_called_;
+  int restart_called_;
+  std::string extension_id_to_return_;
+
+  DISALLOW_COPY_AND_ASSIGN(TestAppContentControlDelegate);
+};
+
+}  // namespace
+
+// Our testing base.
+class AppActivityTest : public AthenaTestBase {
+ public:
+  AppActivityTest() : test_app_content_control_delegate_(NULL) {}
+  virtual ~AppActivityTest() {}
+
+  // AthenaTestBase:
+  virtual void SetUp() OVERRIDE {
+    AthenaTestBase::SetUp();
+    // Create and install our TestAppContentDelegate with instrumentation.
+    test_app_content_control_delegate_ = new TestAppContentControlDelegate();
+    AppRegistry::Get()->SetDelegate(test_app_content_control_delegate_);
+  }
+
+  // A function to create an Activity.
+  TestAppActivity* CreateAppActivity(const std::string& app_id) {
+    TestAppActivity* activity = new TestAppActivity(app_id);
+    ActivityManager::Get()->AddActivity(activity);
+    return activity;
+  }
+
+  void CloseActivity(Activity* activity) {
+    delete activity;
+    RunAllPendingInMessageLoop();
+  }
+
+  // Get the position of the activity in the navigation history.
+  int GetActivityPosition(Activity* activity) {
+    aura::Window* window = activity->GetActivityViewModel()->GetContentsView()
+                               ->GetWidget()->GetNativeWindow();
+    aura::Window::Windows windows = activity->GetWindow()->parent()->children();
+    for (size_t i = 0; i < windows.size(); i++) {
+      if (windows[i] == window)
+        return i;
+    }
+    return -1;
+  }
+
+ protected:
+  TestAppContentControlDelegate* test_app_content_control_delegate() {
+    return test_app_content_control_delegate_;
+  }
+
+ private:
+  TestAppContentControlDelegate* test_app_content_control_delegate_;
+
+  DISALLOW_COPY_AND_ASSIGN(AppActivityTest);
+};
+
+// Only creates one activity and destroys it.
+TEST_F(AppActivityTest, OneAppActivity) {
+  EXPECT_EQ(0, AppRegistry::Get()->NumberOfApplications());
+  {
+    TestAppActivity* app_activity = CreateAppActivity(kDummyApp1);
+    EXPECT_EQ(1, AppRegistry::Get()->NumberOfApplications());
+    EXPECT_EQ(1, app_activity->app_activity_registry()->NumberOfActivities());
+    EXPECT_EQ(AppRegistry::Get()->GetAppActivityRegistry(kDummyApp1, NULL),
+              app_activity->app_activity_registry());
+    CloseActivity(app_activity);
+  }
+  EXPECT_EQ(0, AppRegistry::Get()->NumberOfApplications());
+  EXPECT_EQ(0, test_app_content_control_delegate()->unload_called());
+  EXPECT_EQ(0, test_app_content_control_delegate()->restart_called());
+}
+
+// Test running of two applications.
+TEST_F(AppActivityTest, TwoAppsWithOneActivityEach) {
+  EXPECT_EQ(0, AppRegistry::Get()->NumberOfApplications());
+  {
+    TestAppActivity* app_activity1 = CreateAppActivity(kDummyApp1);
+    EXPECT_EQ(1, AppRegistry::Get()->NumberOfApplications());
+    EXPECT_EQ(1, app_activity1->app_activity_registry()->NumberOfActivities());
+    TestAppActivity* app_activity2 = CreateAppActivity(kDummyApp2);
+    EXPECT_EQ(2, AppRegistry::Get()->NumberOfApplications());
+    EXPECT_EQ(1, app_activity2->app_activity_registry()->NumberOfActivities());
+    EXPECT_EQ(1, app_activity1->app_activity_registry()->NumberOfActivities());
+    CloseActivity(app_activity1);
+    CloseActivity(app_activity2);
+  }
+  EXPECT_EQ(0, AppRegistry::Get()->NumberOfApplications());
+  EXPECT_EQ(0, test_app_content_control_delegate()->unload_called());
+  EXPECT_EQ(0, test_app_content_control_delegate()->restart_called());
+}
+
+// Create and destroy two activities for the same application.
+TEST_F(AppActivityTest, TwoAppActivities) {
+  EXPECT_EQ(0, AppRegistry::Get()->NumberOfApplications());
+  {
+    TestAppActivity* app_activity1 = CreateAppActivity(kDummyApp1);
+    TestAppActivity* app_activity2 = CreateAppActivity(kDummyApp1);
+    EXPECT_EQ(1, AppRegistry::Get()->NumberOfApplications());
+    EXPECT_EQ(2, app_activity1->app_activity_registry()->NumberOfActivities());
+    EXPECT_EQ(app_activity1->app_activity_registry(),
+              app_activity2->app_activity_registry());
+    CloseActivity(app_activity1);
+    EXPECT_EQ(1, AppRegistry::Get()->NumberOfApplications());
+    EXPECT_EQ(1, app_activity2->app_activity_registry()->NumberOfActivities());
+    CloseActivity(app_activity2);
+  }
+  EXPECT_EQ(0, AppRegistry::Get()->NumberOfApplications());
+  {
+    TestAppActivity* app_activity1 = CreateAppActivity(kDummyApp1);
+    TestAppActivity* app_activity2 = CreateAppActivity(kDummyApp1);
+    EXPECT_EQ(1, AppRegistry::Get()->NumberOfApplications());
+    EXPECT_EQ(2, app_activity1->app_activity_registry()->NumberOfActivities());
+    EXPECT_EQ(app_activity1->app_activity_registry(),
+              app_activity2->app_activity_registry());
+    CloseActivity(app_activity2);
+    EXPECT_EQ(1, AppRegistry::Get()->NumberOfApplications());
+    EXPECT_EQ(1, app_activity1->app_activity_registry()->NumberOfActivities());
+    CloseActivity(app_activity1);
+  }
+  EXPECT_EQ(0, AppRegistry::Get()->NumberOfApplications());
+  EXPECT_EQ(0, test_app_content_control_delegate()->unload_called());
+  EXPECT_EQ(0, test_app_content_control_delegate()->restart_called());
+}
+
+// Test unload and the creation of the proxy, then "closing the activity".
+TEST_F(AppActivityTest, TestUnloadFollowedByClose) {
+  EXPECT_EQ(0, AppRegistry::Get()->NumberOfApplications());
+
+  TestAppActivity* app_activity = CreateAppActivity(kDummyApp1);
+  EXPECT_EQ(1, AppRegistry::Get()->NumberOfApplications());
+  AppActivityRegistry* app_activity_registry =
+      app_activity->app_activity_registry();
+  EXPECT_EQ(1, app_activity_registry->NumberOfActivities());
+  EXPECT_EQ(Activity::ACTIVITY_VISIBLE, app_activity->GetCurrentState());
+
+  // Calling Unload now should not do anything since at least one activity in
+  // the registry is still visible.
+  app_activity_registry->Unload();
+  EXPECT_EQ(0, test_app_content_control_delegate()->unload_called());
+
+  // After setting our activity to unloaded however the application should get
+  // unloaded as requested.
+  app_activity->SetCurrentState(Activity::ACTIVITY_UNLOADED);
+  app_activity_registry->Unload();
+  EXPECT_EQ(1, test_app_content_control_delegate()->unload_called());
+
+  // Check that our created application is gone, and instead a proxy got
+  // created.
+  ASSERT_EQ(1, AppRegistry::Get()->NumberOfApplications());
+  ASSERT_EQ(app_activity_registry,
+            AppRegistry::Get()->GetAppActivityRegistry(kDummyApp1, NULL));
+  EXPECT_EQ(0, app_activity_registry->NumberOfActivities());
+  Activity* activity_proxy =
+      app_activity_registry->unloaded_activity_proxy_for_test();
+  ASSERT_TRUE(activity_proxy);
+  EXPECT_NE(app_activity, activity_proxy);
+  EXPECT_EQ(Activity::ACTIVITY_UNLOADED, activity_proxy->GetCurrentState());
+
+  // Close the proxy object and make sure that nothing bad happens.
+  CloseActivity(activity_proxy);
+
+  EXPECT_EQ(0, AppRegistry::Get()->NumberOfApplications());
+  EXPECT_EQ(1, test_app_content_control_delegate()->unload_called());
+  EXPECT_EQ(0, test_app_content_control_delegate()->restart_called());
+}
+
+// Test that when unloading an app while multiple apps / activities are present,
+// the proxy gets created in the correct location.
+TEST_F(AppActivityTest, TestUnloadProxyLocation) {
+  // Set up some activities for some applications.
+  TestAppActivity* app_activity1a = CreateAppActivity(kDummyApp1);
+  TestAppActivity* app_activity2a = CreateAppActivity(kDummyApp2);
+  TestAppActivity* app_activity2b = CreateAppActivity(kDummyApp2);
+  TestAppActivity* app_activity1b = CreateAppActivity(kDummyApp1);
+  EXPECT_EQ(3, GetActivityPosition(app_activity1b));
+  EXPECT_EQ(2, GetActivityPosition(app_activity2b));
+  EXPECT_EQ(1, GetActivityPosition(app_activity2a));
+  EXPECT_EQ(0, GetActivityPosition(app_activity1a));
+
+  // Unload an app and make sure that the proxy is in the newest activity slot.
+  AppActivityRegistry* app_activity_registry =
+      app_activity2a->app_activity_registry();
+  app_activity2a->SetCurrentState(Activity::ACTIVITY_UNLOADED);
+  app_activity2b->SetCurrentState(Activity::ACTIVITY_UNLOADED);
+  app_activity2a->app_activity_registry()->Unload();
+  EXPECT_EQ(0, app_activity_registry->NumberOfActivities());
+  Activity* activity_proxy =
+      app_activity_registry->unloaded_activity_proxy_for_test();
+  RunAllPendingInMessageLoop();
+
+  EXPECT_EQ(2, GetActivityPosition(app_activity1b));
+  EXPECT_EQ(1, GetActivityPosition(activity_proxy));
+  EXPECT_EQ(0, GetActivityPosition(app_activity1a));
+
+  CloseActivity(activity_proxy);
+  CloseActivity(app_activity1b);
+  CloseActivity(app_activity1a);
+}
+
+// Test that an unload with multiple activities of the same app will only unload
+// when all activities were marked for unloading.
+TEST_F(AppActivityTest, TestMultipleActivityUnloadLock) {
+  EXPECT_EQ(0, AppRegistry::Get()->NumberOfApplications());
+
+  TestAppActivity* app_activity1 = CreateAppActivity(kDummyApp1);
+  TestAppActivity* app_activity2 = CreateAppActivity(kDummyApp1);
+  TestAppActivity* app_activity3 = CreateAppActivity(kDummyApp1);
+
+  // Check that we have 3 activities of the same application.
+  EXPECT_EQ(1, AppRegistry::Get()->NumberOfApplications());
+  AppActivityRegistry* app_activity_registry =
+      app_activity1->app_activity_registry();
+  EXPECT_EQ(app_activity_registry, app_activity2->app_activity_registry());
+  EXPECT_EQ(app_activity_registry, app_activity3->app_activity_registry());
+  EXPECT_EQ(3, app_activity_registry->NumberOfActivities());
+  EXPECT_EQ(Activity::ACTIVITY_VISIBLE, app_activity1->GetCurrentState());
+  EXPECT_EQ(Activity::ACTIVITY_VISIBLE, app_activity2->GetCurrentState());
+  EXPECT_EQ(Activity::ACTIVITY_VISIBLE, app_activity3->GetCurrentState());
+
+  // After setting all activities to UNLOADED the application should unload.
+  app_activity1->SetCurrentState(Activity::ACTIVITY_UNLOADED);
+  app_activity1->app_activity_registry()->Unload();
+  EXPECT_EQ(0, test_app_content_control_delegate()->unload_called());
+  app_activity2->SetCurrentState(Activity::ACTIVITY_UNLOADED);
+  app_activity2->app_activity_registry()->Unload();
+  EXPECT_EQ(0, test_app_content_control_delegate()->unload_called());
+  app_activity3->SetCurrentState(Activity::ACTIVITY_UNLOADED);
+  app_activity3->app_activity_registry()->Unload();
+  EXPECT_EQ(1, test_app_content_control_delegate()->unload_called());
+
+  // Now there should only be the proxy activity left.
+  ASSERT_EQ(1, AppRegistry::Get()->NumberOfApplications());
+  ASSERT_EQ(app_activity_registry,
+            AppRegistry::Get()->GetAppActivityRegistry(kDummyApp1, NULL));
+  EXPECT_EQ(0, app_activity_registry->NumberOfActivities());
+  Activity* activity_proxy =
+      app_activity_registry->unloaded_activity_proxy_for_test();
+  ASSERT_TRUE(activity_proxy);
+  EXPECT_NE(app_activity1, activity_proxy);
+  EXPECT_NE(app_activity2, activity_proxy);
+  EXPECT_NE(app_activity3, activity_proxy);
+  EXPECT_EQ(Activity::ACTIVITY_UNLOADED, activity_proxy->GetCurrentState());
+
+  // Close the proxy object and make sure that nothing bad happens.
+  CloseActivity(activity_proxy);
+
+  EXPECT_EQ(0, AppRegistry::Get()->NumberOfApplications());
+  EXPECT_EQ(1, test_app_content_control_delegate()->unload_called());
+  EXPECT_EQ(0, test_app_content_control_delegate()->restart_called());
+}
+
+// Test that activating the proxy will reload the application.
+TEST_F(AppActivityTest, TestUnloadWithReload) {
+  EXPECT_EQ(0, AppRegistry::Get()->NumberOfApplications());
+
+  TestAppActivity* app_activity = CreateAppActivity(kDummyApp1);
+  AppActivityRegistry* app_activity_registry =
+      app_activity->app_activity_registry();
+
+  // Unload the activity.
+  app_activity->SetCurrentState(Activity::ACTIVITY_UNLOADED);
+  app_activity_registry->Unload();
+  EXPECT_EQ(1, test_app_content_control_delegate()->unload_called());
+
+  // Try to activate the activity again. This will force the application to
+  // reload.
+  Activity* activity_proxy =
+      app_activity_registry->unloaded_activity_proxy_for_test();
+  activity_proxy->SetCurrentState(Activity::ACTIVITY_VISIBLE);
+  EXPECT_EQ(1, test_app_content_control_delegate()->restart_called());
+
+  // However - the restart in this test framework does not really restart and
+  // all objects should be gone now.
+  EXPECT_EQ(0, AppRegistry::Get()->NumberOfApplications());
+}
+
+}  // namespace test
+}  // namespace athena
diff --git a/athena/content/app_registry_impl.cc b/athena/content/app_registry_impl.cc
new file mode 100644
index 000000000000..cd32719c9a1f
--- /dev/null
+++ b/athena/content/app_registry_impl.cc
@@ -0,0 +1,108 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "athena/content/public/app_registry.h"
+
+#include "athena/content/app_activity_registry.h"
+#include "athena/content/public/app_content_control_delegate.h"
+#include "base/logging.h"
+
+namespace athena {
+
+class AppRegistryImpl : public AppRegistry {
+ public:
+  AppRegistryImpl();
+  virtual ~AppRegistryImpl();
+
+  // AppRegistry:
+  virtual void SetDelegate(AppContentControlDelegate* delegate) OVERRIDE;
+  virtual AppContentControlDelegate* GetDelegate() OVERRIDE;
+  virtual AppActivityRegistry* GetAppActivityRegistry(
+      const std::string& app_id,
+      content::BrowserContext* browser_context) OVERRIDE;
+  virtual int NumberOfApplications() const OVERRIDE { return app_list_.size(); }
+
+ private:
+  virtual void RemoveAppActivityRegistry(
+      AppActivityRegistry* registry) OVERRIDE;
+
+ std::vector<AppActivityRegistry*> app_list_;
+
+  scoped_ptr<AppContentControlDelegate> delegate_;
+
+  DISALLOW_COPY_AND_ASSIGN(AppRegistryImpl);
+};
+
+namespace {
+
+AppRegistryImpl* instance = NULL;
+
+}  // namespace
+
+AppRegistryImpl::AppRegistryImpl() :
+    delegate_(AppContentControlDelegate::CreateAppContentControlDelegate()) {}
+
+AppRegistryImpl::~AppRegistryImpl() {
+  DCHECK(app_list_.empty());
+}
+
+void AppRegistryImpl::SetDelegate(AppContentControlDelegate* delegate) {
+  DCHECK(delegate);
+  delegate_.reset(delegate);
+}
+
+AppContentControlDelegate* AppRegistryImpl::GetDelegate() {
+  return delegate_.get();
+}
+
+AppActivityRegistry* AppRegistryImpl::GetAppActivityRegistry(
+    const std::string& app_id,
+    content::BrowserContext* browser_context) {
+  // Search for an existing proxy.
+  for (std::vector<AppActivityRegistry*>::iterator it = app_list_.begin();
+       it != app_list_.end(); ++it) {
+    if ((*it)->app_id() == app_id &&
+        (*it)->browser_context() == browser_context)
+      return *it;
+  }
+
+  // Create and return a new application object.
+  AppActivityRegistry* app_activity_registry =
+      new AppActivityRegistry(app_id, browser_context);
+  app_list_.push_back(app_activity_registry);
+  return app_activity_registry;
+}
+
+void AppRegistryImpl::RemoveAppActivityRegistry(AppActivityRegistry* registry) {
+  std::vector<AppActivityRegistry*>::iterator item =
+      std::find(app_list_.begin(), app_list_.end(), registry);
+  CHECK(item != app_list_.end());
+  app_list_.erase(item);
+}
+
+// static
+void AppRegistry::Create() {
+  DCHECK(!instance);
+  instance = new AppRegistryImpl();
+}
+
+// static
+AppRegistry* AppRegistry::Get() {
+  DCHECK(instance);
+  return instance;
+}
+
+// static
+void AppRegistry::ShutDown() {
+  DCHECK(instance);
+  delete instance;
+}
+
+AppRegistry::AppRegistry() {}
+
+AppRegistry::~AppRegistry() {
+  instance = NULL;
+}
+
+}  // namespace athena
diff --git a/athena/content/delegate/app_content_control_delegate_impl.cc b/athena/content/delegate/app_content_control_delegate_impl.cc
new file mode 100644
index 000000000000..967be8f15fb2
--- /dev/null
+++ b/athena/content/delegate/app_content_control_delegate_impl.cc
@@ -0,0 +1,82 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "athena/content/public/app_content_control_delegate.h"
+
+#include "content/public/browser/render_view_host.h"
+#include "content/public/browser/site_instance.h"
+#include "content/public/browser/web_contents.h"
+#include "extensions/browser/api/app_runtime/app_runtime_api.h"
+#include "extensions/browser/extension_registry.h"
+#include "extensions/common/constants.h"
+
+namespace athena {
+
+class AppContentControlDelegateImpl : public AppContentControlDelegate {
+ public:
+  AppContentControlDelegateImpl() {}
+  virtual ~AppContentControlDelegateImpl() {}
+
+  // AppContentControlDelegate:
+  virtual bool UnloadApplication(
+      const std::string& app_id,
+      content::BrowserContext* browser_context) OVERRIDE;
+  virtual bool RestartApplication(
+      const std::string& app_id,
+      content::BrowserContext* browser_context) OVERRIDE;
+  virtual std::string GetApplicationID(
+      content::WebContents* web_contents) OVERRIDE;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(AppContentControlDelegateImpl);
+};
+
+bool AppContentControlDelegateImpl::UnloadApplication(
+    const std::string& app_id,
+    content::BrowserContext* browser_context) {
+  // TODO(skuhne): Use the extension system to unload
+  // (|ExtensionService::TerminateExtension|) once it becomes available in
+  // Athena.
+  return false;
+}
+
+bool AppContentControlDelegateImpl::RestartApplication(
+    const std::string& app_id,
+    content::BrowserContext* browser_context) {
+  // TODO(skuhne): As soon as the ExtensionSystem can be used, we should use the
+  // proper commands here for restarting.
+  const extensions::Extension* extension =
+      extensions::ExtensionRegistry::Get(browser_context)->GetExtensionById(
+          app_id, extensions::ExtensionRegistry::EVERYTHING);
+  DCHECK(extension);
+  extensions::AppRuntimeEventRouter::DispatchOnLaunchedEvent(browser_context,
+                                                             extension);
+  return true;
+}
+
+// Get the extension Id from a given |web_contents|.
+std::string AppContentControlDelegateImpl::GetApplicationID(
+    content::WebContents* web_contents) {
+  content::RenderViewHost* render_view_host = web_contents->GetRenderViewHost();
+  // This works for both apps and extensions because the site has been
+  // normalized to the extension URL for hosted apps.
+  content::SiteInstance* site_instance = render_view_host->GetSiteInstance();
+  if (!site_instance)
+    return std::string();
+
+  const GURL& site_url = site_instance->GetSiteURL();
+
+  if (!site_url.SchemeIs(extensions::kExtensionScheme))
+    return std::string();
+
+  return site_url.host();
+}
+
+// static
+AppContentControlDelegate*
+AppContentControlDelegate::CreateAppContentControlDelegate() {
+  return new AppContentControlDelegateImpl;
+}
+
+}  // namespace athena
diff --git a/athena/content/public/app_content_control_delegate.h b/athena/content/public/app_content_control_delegate.h
new file mode 100644
index 000000000000..ad3e5538fe5e
--- /dev/null
+++ b/athena/content/public/app_content_control_delegate.h
@@ -0,0 +1,40 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef ATHENA_CONTENT_PUBLIC_APP_CONTENT_CONTROL_DLEGATE_H_
+#define ATHENA_CONTENT_PUBLIC_APP_CONTENT_CONTROL_DLEGATE_H_
+
+#include <string>
+
+#include "base/macros.h"
+
+namespace content {
+class BrowserContext;
+class WebContents;
+}
+
+namespace athena {
+
+// The application content delegate which can be overwritten for unit tests to
+// eliminate dependencies to the content / browser system.
+class AppContentControlDelegate {
+ public:
+  static AppContentControlDelegate* CreateAppContentControlDelegate();
+
+  AppContentControlDelegate() {}
+  virtual ~AppContentControlDelegate() {}
+
+  // Unload an application. Returns true when unloaded.
+  virtual bool UnloadApplication(const std::string& app_id,
+                                 content::BrowserContext* browser_context) = 0;
+  // Restarts an application. Returns true when the restart was initiated.
+  virtual bool RestartApplication(const std::string& app_id,
+                                  content::BrowserContext* browser_context) = 0;
+  // Returns the application ID (or an empty string) for a given web content.
+  virtual std::string GetApplicationID(content::WebContents* web_contents) = 0;
+};
+
+}  // namespace athena
+
+#endif  // ATHENA_CONTENT_PUBLIC_APP_CONTENT_CONTROL_DLEGATE_H_
diff --git a/athena/content/public/app_registry.h b/athena/content/public/app_registry.h
new file mode 100644
index 000000000000..c296f2e3b780
--- /dev/null
+++ b/athena/content/public/app_registry.h
@@ -0,0 +1,72 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef ATHENA_CONTENT_PUBLIC_APP_REGISTRY_H_
+#define ATHENA_CONTENT_PUBLIC_APP_REGISTRY_H_
+
+#include <string>
+#include <vector>
+
+#include "athena/athena_export.h"
+#include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+
+namespace content {
+class BrowserContext;
+}
+
+namespace athena {
+
+class AppActivityRegistry;
+class AppContentControlDelegate;
+class AppRegistryImpl;
+
+// This class holds for each application, held by a user, a list of activities.
+// The list of activities can be retrieved as |AppActivityRegistry|. It is used
+// to associate activities with applications and allow the resource manager to
+// (re)start and stop applications.
+class ATHENA_EXPORT AppRegistry {
+ public:
+  // Creates the AppRegistry instance.
+  static void Create();
+
+  // Gets the instance of the controller.
+  static AppRegistry* Get();
+
+  // Shuts down the registry (all applications should be shut down by then).
+  static void ShutDown();
+
+  // Overrides the used AppContentDelegate. This function will own it
+  // afterwards. A value of NULL is invalid.
+  virtual void SetDelegate(AppContentControlDelegate* delegate) = 0;
+
+  // Retrieves the application content delegate. The ownership remains with this
+  // class.
+  virtual AppContentControlDelegate* GetDelegate() = 0;
+
+  // Returns an |AppActivityRegistry| for a given activity |app_id| and
+  // |browser_context|.
+  virtual AppActivityRegistry* GetAppActivityRegistry(
+      const std::string& app_id,
+      content::BrowserContext* browser_context) = 0;
+
+  // Returns the number of registered applications.
+  virtual int NumberOfApplications() const = 0;
+
+ protected:
+  // Only the |AppActivityRegistry| can remove itself.
+  friend AppActivityRegistry;
+
+  // Removes an activity registry for an application from the list of known
+  // applications.
+  virtual void RemoveAppActivityRegistry(AppActivityRegistry* registry) = 0;
+
+  // Constructor and destructor can only be called by the implementing class.
+  AppRegistry();
+  virtual ~AppRegistry();
+};
+
+}  // namespace athena
+
+#endif  // ATHENA_CONTENT_PUBLIC_APP_REGISTRY_H_
diff --git a/athena/content/web_activity.cc b/athena/content/web_activity.cc
index 35e0d71553d0..e4eb00688ee4 100644
--- a/athena/content/web_activity.cc
+++ b/athena/content/web_activity.cc
@@ -347,6 +347,10 @@ Activity::ActivityMediaState WebActivity::GetMediaState() {
   return Activity::ACTIVITY_MEDIA_STATE_NONE;
 }
 
+aura::Window* WebActivity::GetWindow() {
+  return !web_view_ ? NULL : web_view_->GetWidget()->GetNativeWindow();
+}
+
 void WebActivity::Init() {
   DCHECK(web_view_);
   web_view_->InstallAccelerators();
diff --git a/athena/content/web_activity.h b/athena/content/web_activity.h
index 6e3f41ba0e0e..e421f6f621e6 100644
--- a/athena/content/web_activity.h
+++ b/athena/content/web_activity.h
@@ -39,6 +39,7 @@ class WebActivity : public Activity,
   virtual ActivityState GetCurrentState() OVERRIDE;
   virtual bool IsVisible() OVERRIDE;
   virtual ActivityMediaState GetMediaState() OVERRIDE;
+  virtual aura::Window* GetWindow() OVERRIDE;
 
   // ActivityViewModel:
   virtual void Init() OVERRIDE;
diff --git a/athena/main/athena_launcher.cc b/athena/main/athena_launcher.cc
index de4dbc748c62..21faf6bb7f69 100644
--- a/athena/main/athena_launcher.cc
+++ b/athena/main/athena_launcher.cc
@@ -6,6 +6,7 @@
 
 #include "athena/activity/public/activity_factory.h"
 #include "athena/activity/public/activity_manager.h"
+#include "athena/content/public/app_registry.h"
 #include "athena/content/public/content_activity_factory.h"
 #include "athena/content/public/content_app_model_builder.h"
 #include "athena/home/public/home_card.h"
@@ -119,6 +120,7 @@ void StartAthenaEnv(aura::Window* root_window,
   athena::InputManager::Create()->OnRootWindowCreated(root_window);
   athena::ScreenManager::Create(delegate, root_window);
   athena::WindowManager::Create();
+  athena::AppRegistry::Create();
   SetupBackgroundImage();
 
   athena::ScreenManager::Get()->GetContext()->SetProperty(
@@ -151,6 +153,7 @@ void ShutdownAthena() {
   athena::ActivityFactory::Shutdown();
   athena::ActivityManager::Shutdown();
   athena::HomeCard::Shutdown();
+  athena::AppRegistry::ShutDown();
   athena::WindowManager::Shutdown();
   athena::ScreenManager::Shutdown();
   athena::InputManager::Shutdown();
diff --git a/athena/main/athena_main.gyp b/athena/main/athena_main.gyp
index c4641a88493d..b9a075f66179 100644
--- a/athena/main/athena_main.gyp
+++ b/athena/main/athena_main.gyp
@@ -13,6 +13,7 @@
       'dependencies': [
         '../athena.gyp:athena_lib',
         '../athena.gyp:athena_content_lib',
+        '../athena.gyp:athena_content_support_lib',
         '../resources/athena_resources.gyp:athena_resources',
 	# debug_widow.cc depends on this. Remove this once debug_window
 	# is removed.
diff --git a/athena/test/DEPS b/athena/test/DEPS
index ded0bbd43c8c..e938483b40a3 100644
--- a/athena/test/DEPS
+++ b/athena/test/DEPS
@@ -1,5 +1,6 @@
 include_rules = [
   "+athena/activity",
+  "+athena/content/public",
   "+athena/home/public",
   "+athena/main",
   "+athena/screen/public",
diff --git a/athena/test/sample_activity.cc b/athena/test/sample_activity.cc
index 6c4c06486c90..8e36ea069bc3 100644
--- a/athena/test/sample_activity.cc
+++ b/athena/test/sample_activity.cc
@@ -6,6 +6,7 @@
 
 #include "ui/views/background.h"
 #include "ui/views/view.h"
+#include "ui/views/widget/widget.h"
 
 namespace athena {
 namespace test {
@@ -43,6 +44,11 @@ Activity::ActivityMediaState SampleActivity::GetMediaState() {
   return Activity::ACTIVITY_MEDIA_STATE_NONE;
 }
 
+aura::Window* SampleActivity::GetWindow() {
+   return
+       !contents_view_ ? NULL : contents_view_->GetWidget()->GetNativeWindow();
+}
+
 void SampleActivity::Init() {
 }
 
diff --git a/athena/test/sample_activity.h b/athena/test/sample_activity.h
index 7f7432a3c430..a43d60986d03 100644
--- a/athena/test/sample_activity.h
+++ b/athena/test/sample_activity.h
@@ -28,6 +28,7 @@ class SampleActivity : public Activity,
   virtual ActivityState GetCurrentState() OVERRIDE;
   virtual bool IsVisible() OVERRIDE;
   virtual ActivityMediaState GetMediaState() OVERRIDE;
+  virtual aura::Window* GetWindow() OVERRIDE;
 
   // athena::ActivityViewModel:
   virtual void Init() OVERRIDE;
diff --git a/athena/test/test_app_content_control_delegate_impl.cc b/athena/test/test_app_content_control_delegate_impl.cc
new file mode 100644
index 000000000000..0cecfecd6e2b
--- /dev/null
+++ b/athena/test/test_app_content_control_delegate_impl.cc
@@ -0,0 +1,53 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "athena/content/public/app_content_control_delegate.h"
+
+namespace athena {
+
+class AppContentControlDelegateImpl : public AppContentControlDelegate {
+ public:
+  AppContentControlDelegateImpl() {}
+  virtual ~AppContentControlDelegateImpl() {}
+
+  virtual bool UnloadApplication(
+      const std::string& app_id,
+      content::BrowserContext* browser_context) OVERRIDE;
+  virtual bool RestartApplication(
+      const std::string& app_id,
+      content::BrowserContext* browser_context) OVERRIDE;
+  virtual std::string GetApplicationID(
+      content::WebContents* web_contents) OVERRIDE;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(AppContentControlDelegateImpl);
+};
+
+bool AppContentControlDelegateImpl::UnloadApplication(
+    const std::string& app_id,
+    content::BrowserContext* browser_context) {
+  // TODO(skuhne): Use the extension system to unload
+  // (|ExtensionService::TerminateExtension|) once it becomes available in
+  // Athena.
+  return false;
+}
+
+bool AppContentControlDelegateImpl::RestartApplication(
+    const std::string& app_id,
+    content::BrowserContext* browser_context) {
+  return false;
+}
+
+std::string AppContentControlDelegateImpl::GetApplicationID(
+    content::WebContents* web_contents) {
+  return std::string();
+}
+
+// static
+AppContentControlDelegate*
+AppContentControlDelegate::CreateAppContentControlDelegate() {
+  return new AppContentControlDelegateImpl;
+}
+
+}  // namespace athena