Use unique URLs rather than qualifiers to uniquify RenderProcesses.

This is so code in the browser has something tangible to call ConnectToApplication() on. When a RenderProcessHost creates a new renderer, it creates a URL of the style exe:chrome_renderer#, where # is the RenderProcess ID. It stores this string on the RenderProcessHost's SupportsUserData. Call content/browser/mojo/mojo_shell_client_host.h's GetMojoApplicationInstanceURL() with a particular RPH to get the URL to connect to it.

R=jam@chromium.org
http://crbug.com/558009

Review URL: https://codereview.chromium.org/1455323002

Cr-Commit-Position: refs/heads/master@{#360604}

content/browser/mojo/mojo_shell_client_host.cc

@@ -2,9 +2,11 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+#include "base/strings/stringprintf.h"
 #include "base/thread_task_runner_handle.h"
 #include "content/browser/mojo/mojo_shell_client_host.h"
 #include "content/common/mojo/mojo_messages.h"
+#include "content/public/browser/render_process_host.h"
 #include "content/public/common/mojo_shell_connection.h"
 #include "ipc/ipc_sender.h"
 #include "mojo/application/public/cpp/application_impl.h"
@@ -16,6 +18,9 @@
 
 namespace content {
 namespace {
+
+const char kMojoShellInstanceURL[] = "mojo_shell_instance_url";
+
 void DidCreateChannel(mojo::embedder::ChannelInfo* info) {}
 
 base::PlatformFile PlatformFileFromScopedPlatformHandle(
@@ -27,11 +32,30 @@ base::PlatformFile PlatformFileFromScopedPlatformHandle(
 #endif
 }
 
+class InstanceURL : public base::SupportsUserData::Data {
+ public:
+  InstanceURL(const std::string& instance_url) : instance_url_(instance_url) {}
+  ~InstanceURL() override {}
+
+  std::string get() const { return instance_url_; }
+
+ private:
+  std::string instance_url_;
+
+  DISALLOW_COPY_AND_ASSIGN(InstanceURL);
+};
+
+void SetMojoApplicationInstanceURL(RenderProcessHost* render_process_host,
+                                   const std::string& instance_url) {
+  render_process_host->SetUserData(kMojoShellInstanceURL,
+                                   new InstanceURL(instance_url));
+}
+
 }  // namespace
 
 void RegisterChildWithExternalShell(int child_process_id,
                                     base::ProcessHandle process_handle,
-                                    IPC::Sender* sender) {
+                                    RenderProcessHost* render_process_host) {
   // Some process types get created before the main message loop.
   if (!MojoShellConnection::Get())
     return;
@@ -57,16 +81,27 @@ void RegisterChildWithExternalShell(int child_process_id,
   //             specification is best determined (not here, this is a common
   //             chokepoint for all process types) and how to wire it through.
   //             http://crbug.com/555393
+  std::string url =
+      base::StringPrintf("exe:chrome_renderer%d", child_process_id);
   application_manager->CreateInstanceForHandle(
-      mojo::ScopedHandle(mojo::Handle(handle.release().value())),
-      "exe:chrome_renderer",  // See above about how this string is meaningless.
-      base::IntToString(child_process_id));
+      mojo::ScopedHandle(mojo::Handle(handle.release().value())), url);
 
   // Send the other end to the child via Chrome IPC.
   base::PlatformFile client_file = PlatformFileFromScopedPlatformHandle(
       platform_channel_pair.PassClientHandle());
-  sender->Send(new MojoMsg_BindExternalMojoShellHandle(
+  render_process_host->Send(new MojoMsg_BindExternalMojoShellHandle(
       IPC::GetFileHandleForProcess(client_file, process_handle, true)));
+
+  // Store the URL on the RPH so client code can access it later via
+  // GetMojoApplicationInstanceURL().
+  SetMojoApplicationInstanceURL(render_process_host, url);
+}
+
+std::string GetMojoApplicationInstanceURL(
+    RenderProcessHost* render_process_host) {
+  InstanceURL* instance_url = static_cast<InstanceURL*>(
+      render_process_host->GetUserData(kMojoShellInstanceURL));
+  return instance_url ? instance_url->get() : std::string();
 }
 
 }  // namespace content

content/browser/mojo/mojo_shell_client_host.h

@@ -5,22 +5,28 @@
 #ifndef CONTENT_BROWSER_MOJO_MOJO_SHELL_CLIENT_HOST_H_
 #define CONTENT_BROWSER_MOJO_MOJO_SHELL_CLIENT_HOST_H_
 
-#include "base/process/process_handle.h"
+#include <string>
 
-namespace IPC {
-class Sender;
-}
+#include "base/process/process_handle.h"
 
 namespace content {
 
+class RenderProcessHost;
+
 // Creates a communication channel between the external Mojo shell and the
 // child. The server handle of this channel is shared with the external shell
 // via Mojo IPC and the client handle is shared with the child via Chrome IPC.
 // |child_process_id| is used to uniquify the child in the external shell's
 // instance map.
 void RegisterChildWithExternalShell(int child_process_id,
                                     base::ProcessHandle process_handle,
-                                    IPC::Sender* sender);
+                                    RenderProcessHost* render_process_host);
+
+// Returns the URL associated with an instance corresponding to the renderer
+// process in the external shell. This URL can be passed to
+// ConnectToApplication() to open a new connection to this renderer.
+std::string GetMojoApplicationInstanceURL(
+    RenderProcessHost* render_process_host);
 
 }  // namespace content
 

mojo/shell/application_manager.cc

@@ -117,15 +117,14 @@ ApplicationInstance* ApplicationManager::GetApplicationInstance(
 }
 
 void ApplicationManager::CreateInstanceForHandle(ScopedHandle channel,
-                                                 const GURL& url,
-                                                 const std::string& qualifier) {
+                                                 const GURL& url) {
   // Instances created by others are considered unique, and thus have no
   // identity. As such they cannot be connected to by anyone else, and so we
   // never call ConnectToClient().
   // TODO(beng): GetPermissiveCapabilityFilter() here obviously cannot make it
   //             to production. See note in application_manager.mojom.
   //             http://crbug.com/555392
-  Identity target_id(url, qualifier, GetPermissiveCapabilityFilter());
+  Identity target_id(url, std::string(), GetPermissiveCapabilityFilter());
   InterfaceRequest<Application> application_request =
       CreateInstance(target_id, base::Closure(), nullptr);
   NativeRunner* runner =

mojo/shell/application_manager.h

@@ -92,9 +92,7 @@ class ApplicationManager {
 
   ApplicationInstance* GetApplicationInstance(const Identity& identity) const;
 
-  void CreateInstanceForHandle(ScopedHandle channel,
-                               const GURL& url,
-                               const std::string& qualifier);
+  void CreateInstanceForHandle(ScopedHandle channel, const GURL& url);
 
  private:
   using IdentityToInstanceMap = std::map<Identity, ApplicationInstance*>;

mojo/shell/application_manager.mojom

@@ -16,5 +16,5 @@ interface ApplicationManager {
   //             otherwise child processes registered with the shell will be
   //             able to request any application/service.
   //             http://crbug.com/555392
-  CreateInstanceForHandle(handle channel, string url, string qualifier);
+  CreateInstanceForHandle(handle channel, string url);
 };

mojo/shell/shell_application_delegate.cc

@@ -28,11 +28,9 @@ void ShellApplicationDelegate::Create(
   bindings_.AddBinding(this, request.Pass());
 }
 
-void ShellApplicationDelegate::CreateInstanceForHandle(
-    ScopedHandle channel,
-    const String& url,
-    const String& qualifier) {
-  manager_->CreateInstanceForHandle(channel.Pass(), GURL(url), qualifier);
+void ShellApplicationDelegate::CreateInstanceForHandle(ScopedHandle channel,
+                                                       const String& url) {
+  manager_->CreateInstanceForHandle(channel.Pass(), GURL(url));
 }
 
 }  // namespace shell

mojo/shell/shell_application_delegate.h

@@ -36,8 +36,7 @@ class ShellApplicationDelegate
 
   // Overridden from mojom::ApplicationManager:
   void CreateInstanceForHandle(ScopedHandle channel,
-                               const String& url,
-                               const String& qualifier) override;
+                               const String& url) override;
 
   mojo::shell::ApplicationManager* manager_;