555154c1e9934041ee008a84b96894cab51e924e.diff

diff --git a/chrome/browser/ui/color/win/native_chrome_color_mixer_win.cc b/chrome/browser/ui/color/win/native_chrome_color_mixer_win.cc
index a9521f587881e..82d23a37daa43 100644
--- a/chrome/browser/ui/color/win/native_chrome_color_mixer_win.cc
+++ b/chrome/browser/ui/color/win/native_chrome_color_mixer_win.cc
@@ -30,6 +30,13 @@
 #include "ui/views/views_features.h"
 
 namespace {
+
+SkColor GetDefaultInactiveFrameColor() {
+  return base::win::GetVersion() < base::win::Version::WIN10
+             ? SkColorSetRGB(0xEB, 0xEB, 0xEB)
+             : SK_ColorWHITE;
+}
+
 // This class encapsulates much of the same logic from ThemeHelperWin pertaining
 // to the calculation of frame colors on Windows 8, 10 and up. Once the
 // ColorProvider is permanently switched on, all the relevant code from
@@ -145,7 +152,7 @@ void FrameColorHelper::AddNativeChromeColors(
       } else if (ShouldDefaultThemeUseMicaTitlebar()) {
         inactive_frame_transform = {key.color_mode == ColorMode::kDark
                                         ? kSystemMicaDarkFrameColor
-                                        : kSystemMicaLightFrameColor};
+                                        : GetDefaultInactiveFrameColor()};
       }
     }
 
@@ -225,7 +232,8 @@ bool FrameColorHelper::DwmColorsAllowed(
     const ui::ColorProviderKey& key) const {
   const bool use_native_frame_if_enabled =
       (!ShouldAlwaysUseSystemTitlebar() ||
-       !HasCustomImage(IDR_THEME_FRAME, key));
+       !HasCustomImage(IDR_THEME_FRAME, key)) &&
+      (base::win::GetVersion() >= base::win::Version::WIN8);
   return use_native_frame_if_enabled && ui::win::IsAeroGlassEnabled();
 }
 
@@ -265,10 +273,14 @@ void FrameColorHelper::FetchAccentColors() {
   }
 
   dwm_accent_border_color_ =
-      accent_color_observer->accent_border_color().value_or(SK_ColorWHITE);
+      accent_color_observer->accent_border_color().value_or(GetDefaultInactiveFrameColor());
 
-  dwm_frame_color_ = accent_color;
-  dwm_inactive_frame_color_ = accent_color_observer->accent_color_inactive();
+  if (base::win::GetVersion() < base::win::Version::WIN10) {
+    dwm_frame_color_ = dwm_accent_border_color_;
+  } else {
+    dwm_frame_color_ = accent_color_observer->accent_color();
+    dwm_inactive_frame_color_ = accent_color_observer->accent_color_inactive();
+  }
 }
 
 ui::ColorTransform GetCaptionForegroundColor(
diff --git a/chrome/browser/ui/startup/startup_browser_creator_browsertest.cc b/chrome/browser/ui/startup/startup_browser_creator_browsertest.cc
index abb93ab01626f..e59f96e5653c9 100644
--- a/chrome/browser/ui/startup/startup_browser_creator_browsertest.cc
+++ b/chrome/browser/ui/startup/startup_browser_creator_browsertest.cc
@@ -170,6 +170,10 @@
 using testing::Return;
 #endif  // !BUILDFLAG(IS_CHROMEOS_ASH)
 
+#if BUILDFLAG(IS_WIN)
+#include "base/win/windows_version.h"
+#endif
+
 #if BUILDFLAG(IS_MAC)
 #include "chrome/browser/apps/app_shim/app_shim_manager_mac.h"
 #include "chrome/browser/chrome_browser_application_mac.h"
@@ -207,6 +211,14 @@ Browser* FindOneOtherBrowser(Browser* browser) {
   return other_browser;
 }
 
+bool IsWindows10OrNewer() {
+#if BUILDFLAG(IS_WIN)
+  return base::win::GetVersion() >= base::win::Version::WIN10;
+#else
+  return false;
+#endif
+}
+
 void DisableWhatsNewPage() {
   PrefService* pref_service = g_browser_process->local_state();
   pref_service->SetInteger(prefs::kLastWhatsNewVersion, CHROME_VERSION_MAJOR);
@@ -2598,6 +2610,14 @@ class StartupBrowserWebAppProtocolHandlingTest : public InProcessBrowserTest {
  protected:
   StartupBrowserWebAppProtocolHandlingTest() = default;
 
+  bool AreProtocolHandlersSupported() {
+#if BUILDFLAG(IS_WIN)
+    return base::win::GetVersion() > base::win::Version::WIN7;
+#else
+    return true;
+#endif
+  }
+
   void SetUpOnMainThread() override {
     InProcessBrowserTest::SetUpOnMainThread();
   }
@@ -2665,6 +2685,9 @@ class StartupBrowserWebAppProtocolHandlingTest : public InProcessBrowserTest {
 IN_PROC_BROWSER_TEST_F(
     StartupBrowserWebAppProtocolHandlingTest,
     WebAppLaunch_WebAppIsNotLaunchedWithProtocolUrlAndDialogCancel) {
+  if (!AreProtocolHandlersSupported())
+    GTEST_SKIP() << "Protocol Handlers unsupported";
+
   views::NamedWidgetShownWaiter waiter(views::test::AnyWidgetTestPasskey{},
                                        "ProtocolHandlerLaunchDialogView");
 
@@ -2689,6 +2712,9 @@ IN_PROC_BROWSER_TEST_F(
 IN_PROC_BROWSER_TEST_F(
     StartupBrowserWebAppProtocolHandlingTest,
     WebAppLaunch_WebAppIsLaunchedWithProtocolUrlAndDialogAccept) {
+  if (!AreProtocolHandlersSupported())
+    GTEST_SKIP() << "Protocol Handlers unsupported";
+
   views::NamedWidgetShownWaiter waiter(views::test::AnyWidgetTestPasskey{},
                                        "ProtocolHandlerLaunchDialogView");
 
@@ -2742,6 +2768,9 @@ IN_PROC_BROWSER_TEST_F(
 IN_PROC_BROWSER_TEST_F(
     StartupBrowserWebAppProtocolHandlingTest,
     WebAppLaunch_WebAppIsNotTranslatedWithUnhandledProtocolUrl) {
+  if (!AreProtocolHandlersSupported())
+    GTEST_SKIP() << "Protocol Handlers unsupported";
+
   // Register web app as a protocol handler that should *not* handle the launch.
   apps::ProtocolHandlerInfo protocol_handler;
   const std::string handler_url = std::string(kStartUrl) + "/testing=%s";
@@ -2772,6 +2801,9 @@ IN_PROC_BROWSER_TEST_F(
 IN_PROC_BROWSER_TEST_F(
     StartupBrowserWebAppProtocolHandlingTest,
     WebAppLaunch_WebAppIsLaunchedWithAllowedProtocolUrlPref) {
+  if (!AreProtocolHandlersSupported())
+    GTEST_SKIP() << "Protocol Handlers unsupported";
+
   views::NamedWidgetShownWaiter waiter(views::test::AnyWidgetTestPasskey{},
                                        "ProtocolHandlerLaunchDialogView");
 
@@ -2838,6 +2870,9 @@ IN_PROC_BROWSER_TEST_F(
 
 IN_PROC_BROWSER_TEST_F(StartupBrowserWebAppProtocolHandlingTest,
                        WebAppLaunch_WebAppIsLaunchedWithAllowedProtocol) {
+  if (!AreProtocolHandlersSupported())
+    GTEST_SKIP() << "Protocol Handlers unsupported";
+
   // Register web app as a protocol handler that should handle the launch.
   apps::ProtocolHandlerInfo protocol_handler;
   const std::string handler_url = std::string(kStartUrl) + "/testing=%s";
@@ -2907,6 +2942,9 @@ IN_PROC_BROWSER_TEST_F(StartupBrowserWebAppProtocolHandlingTest,
 IN_PROC_BROWSER_TEST_F(
     StartupBrowserWebAppProtocolHandlingTest,
     WebAppLaunch_WebAppIsLaunchedWithDiallowedProtocolUrlPref) {
+  if (!AreProtocolHandlersSupported())
+    GTEST_SKIP() << "Protocol Handlers unsupported";
+
   views::NamedWidgetShownWaiter waiter(views::test::AnyWidgetTestPasskey{},
                                        "ProtocolHandlerLaunchDialogView");
 
@@ -2942,6 +2980,9 @@ IN_PROC_BROWSER_TEST_F(
 IN_PROC_BROWSER_TEST_F(
     StartupBrowserWebAppProtocolHandlingTest,
     WebAppLaunch_WebAppIsLaunchedWithDisallowedOnceProtocol) {
+  if (!AreProtocolHandlersSupported())
+    GTEST_SKIP() << "Protocol Handlers unsupported";
+
   // Register web app as a protocol handler that should handle the launch.
   apps::ProtocolHandlerInfo protocol_handler;
   const std::string handler_url = std::string(kStartUrl) + "/testing=%s";
@@ -2994,6 +3035,9 @@ class StartupBrowserWebAppProtocolAndFileHandlingTest
 // handling launch, not a protocol handling or URL launch.
 IN_PROC_BROWSER_TEST_F(StartupBrowserWebAppProtocolAndFileHandlingTest,
                        WebAppLaunch_FileProtocol) {
+  if (!AreProtocolHandlersSupported())
+    GTEST_SKIP() << "Protocol Handlers unsupported";
+
   // Install an app with protocol handlers and a handler for plain text files.
   apps::ProtocolHandlerInfo protocol_handler;
   const std::string handler_url = std::string(kStartUrl) + "/protocol=%s";
@@ -3157,9 +3201,8 @@ IN_PROC_BROWSER_TEST_P(StartupBrowserCreatorFirstRunTest, AddFirstRunTabs) {
 #endif
 IN_PROC_BROWSER_TEST_F(StartupBrowserCreatorFirstRunTest,
                        MAYBE_RestoreOnStartupURLsPolicySpecified) {
-#if BUILDFLAG(IS_WIN)
-  return;
-#endif  // BUILDFLAG(IS_WIN)
+  if (IsWindows10OrNewer())
+    return;
 
   ASSERT_TRUE(embedded_test_server()->Start());
   StartupBrowserCreator browser_creator;
diff --git a/chrome/browser/ui/views/apps/app_window_frame_view_win.cc b/chrome/browser/ui/views/apps/app_window_frame_view_win.cc
index cdd99c6adf68c..a84a3bd3ce4ff 100644
--- a/chrome/browser/ui/views/apps/app_window_frame_view_win.cc
+++ b/chrome/browser/ui/views/apps/app_window_frame_view_win.cc
@@ -6,8 +6,7 @@
 
 #include <windows.h>
 
-#include <algorithm>
-
+#include "base/win/windows_version.h"
 #include "extensions/browser/app_window/native_app_window.h"
 #include "ui/base/hit_test.h"
 #include "ui/base/metadata/metadata_impl_macros.h"
@@ -33,13 +32,32 @@ gfx::Insets AppWindowFrameViewWin::GetFrameInsets() const {
       display::win::ScreenWin::GetSystemMetricsInDIP(SM_CYSIZEFRAME) +
       display::win::ScreenWin::GetSystemMetricsInDIP(SM_CYCAPTION);
 
-  return gfx::Insets::TLBR(caption_height, 0, 0, 0);
+  int frame_size =
+      base::win::GetVersion() < base::win::Version::WIN10
+          ? display::win::ScreenWin::GetSystemMetricsInDIP(SM_CXSIZEFRAME)
+          : 0;
+
+  return gfx::Insets::TLBR(caption_height, frame_size, frame_size, frame_size);
 }
 
 gfx::Insets AppWindowFrameViewWin::GetClientAreaInsets(HMONITOR monitor) const {
-  const int frame_thickness = ui::GetFrameThickness(monitor);
-  return gfx::Insets::TLBR(0, frame_thickness, frame_thickness,
-                           frame_thickness);
+  gfx::Insets insets;
+  if (base::win::GetVersion() < base::win::Version::WIN10) {
+    // This tells Windows that most of the window is a client area, meaning
+    // Chrome will draw it. Windows still fills in the glass bits because of the
+    // DwmExtendFrameIntoClientArea call in |UpdateDWMFrame|.
+    // Without this 1 pixel offset on the right and bottom:
+    //   * windows paint in a more standard way, and
+    //   * we get weird black bars at the top when maximized in multiple monitor
+    //     configurations.
+    int border_thickness = 1;
+    insets = gfx::Insets::TLBR(0, 0, border_thickness, border_thickness);
+  } else {
+    const int frame_thickness = ui::GetFrameThickness(monitor);
+    insets =
+        gfx::Insets::TLBR(0, frame_thickness, frame_thickness, frame_thickness);
+  }
+  return insets;
 }
 
 gfx::Rect AppWindowFrameViewWin::GetBoundsForClientView() const {
diff --git a/chrome/browser/ui/views/bookmarks/bookmark_bar_view_test.cc b/chrome/browser/ui/views/bookmarks/bookmark_bar_view_test.cc
index c94f585b552e9..b28a93cc18c4d 100644
--- a/chrome/browser/ui/views/bookmarks/bookmark_bar_view_test.cc
+++ b/chrome/browser/ui/views/bookmarks/bookmark_bar_view_test.cc
@@ -84,6 +84,7 @@
 #endif
 
 #if BUILDFLAG(IS_WIN)
+#include "base/win/windows_version.h"
 #include "ui/aura/window_tree_host.h"
 #endif
 
@@ -1608,6 +1609,14 @@ class BookmarkBarViewTest17 : public BookmarkBarViewEventTestBase {
 
  protected:
   void DoTestOnMessageLoop() override {
+#if BUILDFLAG(IS_WIN)
+    // TODO(crbug.com/453796): Flaky on Windows7.
+    if (base::win::GetVersion() <= base::win::Version::WIN7) {
+      Done();
+      return;
+    }
+#endif
+
     // Move the mouse to the "All Bookmarks" button and press the left mouse
     // button.
     OpenMenuByClick(bb_view_->all_bookmarks_button(),
diff --git a/chrome/browser/ui/views/create_application_shortcut_view.cc b/chrome/browser/ui/views/create_application_shortcut_view.cc
index 2a60e28a136f0..2ccee19953946 100644
--- a/chrome/browser/ui/views/create_application_shortcut_view.cc
+++ b/chrome/browser/ui/views/create_application_shortcut_view.cc
@@ -30,6 +30,7 @@
 
 #if BUILDFLAG(IS_WIN)
 #include "base/win/shortcut.h"
+#include "base/win/windows_version.h"
 #include "chrome/installer/util/taskbar_util.h"
 #endif  // BUILDFLAG(IS_WIN)
 
@@ -131,9 +132,14 @@ void CreateChromeApplicationShortcutView::InitControls() {
   std::unique_ptr<views::Checkbox> pin_to_taskbar_checkbox;
 
 #if BUILDFLAG(IS_WIN)
-  menu_check_box = AddCheckbox(
-      l10n_util::GetStringUTF16(IDS_CREATE_SHORTCUTS_START_MENU_CHKBOX),
-      prefs::kWebAppCreateInAppsMenu);
+  base::win::Version version = base::win::GetVersion();
+  // Do not allow creating shortcuts on the Start Screen for Windows 8.
+  if (version != base::win::Version::WIN8 &&
+      version != base::win::Version::WIN8_1) {
+    menu_check_box = AddCheckbox(
+        l10n_util::GetStringUTF16(IDS_CREATE_SHORTCUTS_START_MENU_CHKBOX),
+        prefs::kWebAppCreateInAppsMenu);
+  }
 
   // Only include the pin-to-taskbar option when running on versions of Windows
   // that support pinning.
diff --git a/chrome/browser/ui/views/frame/browser_desktop_window_tree_host_win.cc b/chrome/browser/ui/views/frame/browser_desktop_window_tree_host_win.cc
index eca31bb82943f..c1306870f51ea 100644
--- a/chrome/browser/ui/views/frame/browser_desktop_window_tree_host_win.cc
+++ b/chrome/browser/ui/views/frame/browser_desktop_window_tree_host_win.cc
@@ -264,6 +264,9 @@ bool BrowserDesktopWindowTreeHostWin::UsesNativeSystemMenu() const {
 void BrowserDesktopWindowTreeHostWin::Init(
     const views::Widget::InitParams& params) {
   DesktopWindowTreeHostWin::Init(params);
+  if (base::win::GetVersion() < base::win::Version::WIN10)
+    return;  // VirtualDesktopManager isn't supported pre Win-10.
+
   virtual_desktop_helper_ = new VirtualDesktopHelper(params.workspace);
   virtual_desktop_helper_->Init(GetHWND());
 }
@@ -369,12 +372,20 @@ bool BrowserDesktopWindowTreeHostWin::GetDwmFrameInsetsInPixels(
     *insets = gfx::Insets();
   } else {
     // The glass should extend to the bottom of the tabstrip.
+    HWND hwnd = GetHWND();
     gfx::Rect tabstrip_region_bounds(browser_frame_->GetBoundsForTabStripRegion(
         browser_view_->tab_strip_region_view()->GetMinimumSize()));
-    tabstrip_region_bounds = display::win::ScreenWin::DIPToClientRect(
-        GetHWND(), tabstrip_region_bounds);
-
-    *insets = gfx::Insets::TLBR(tabstrip_region_bounds.bottom(), 0, 0, 0);
+    tabstrip_region_bounds =
+        display::win::ScreenWin::DIPToClientRect(hwnd, tabstrip_region_bounds);
+
+    // The 2 px (not DIP) at the inner edges of Win 7 glass are a light and dark
+    // line, so we must inset further to account for those.
+    constexpr int kWin7GlassInset = 2;
+    const int inset = (base::win::GetVersion() < base::win::Version::WIN8)
+                          ? kWin7GlassInset
+                          : 0;
+    *insets = gfx::Insets::TLBR(tabstrip_region_bounds.bottom() + inset, inset,
+                                inset, inset);
   }
   return true;
 }
@@ -474,6 +485,9 @@ void BrowserDesktopWindowTreeHostWin::PostHandleMSG(UINT message,
 }
 
 views::FrameMode BrowserDesktopWindowTreeHostWin::GetFrameMode() const {
+  if (IsOpaqueHostedAppFrame())
+    return views::FrameMode::CUSTOM_DRAWN;
+
   const views::FrameMode system_frame_mode =
       ShouldBrowserCustomDrawTitlebar(browser_view_)
           ? views::FrameMode::SYSTEM_DRAWN_NO_CONTROLS
@@ -503,6 +517,9 @@ bool BrowserDesktopWindowTreeHostWin::ShouldUseNativeFrame() const {
   if (!browser_view_->browser())
     return false;
 
+  if (IsOpaqueHostedAppFrame())
+    return false;
+
   // We don't theme popup or app windows, so regardless of whether or not a
   // theme is active for normal browser windows, we don't want to use the custom
   // frame for popups/apps.
@@ -567,6 +584,13 @@ void BrowserDesktopWindowTreeHostWin::UpdateWorkspace() {
                      weak_factory_.GetWeakPtr()));
 }
 
+bool BrowserDesktopWindowTreeHostWin::IsOpaqueHostedAppFrame() const {
+  // TODO(https://crbug.com/868239): Support Windows 7 Aero glass for web-app
+  // window titlebar controls.
+  return browser_view_->GetIsWebAppType() &&
+         base::win::GetVersion() < base::win::Version::WIN10;
+}
+
 SkBitmap GetBadgedIconBitmapForProfile(Profile* profile) {
   std::unique_ptr<gfx::ImageFamily> family = GetAppIconImageFamily();
   if (!family)
diff --git a/chrome/browser/ui/views/frame/browser_desktop_window_tree_host_win.h b/chrome/browser/ui/views/frame/browser_desktop_window_tree_host_win.h
index a3bd2e0cae1d3..e52ca6cb5dd3f 100644
--- a/chrome/browser/ui/views/frame/browser_desktop_window_tree_host_win.h
+++ b/chrome/browser/ui/views/frame/browser_desktop_window_tree_host_win.h
@@ -88,6 +88,8 @@ class BrowserDesktopWindowTreeHostWin
   // WindowTreeHost of its value.
   void UpdateWorkspace();
 
+  bool IsOpaqueHostedAppFrame() const;
+
   void SetWindowIcon(bool badged);
 
   raw_ptr<BrowserView> browser_view_;
diff --git a/chrome/browser/ui/views/frame/browser_frame_view_win.cc b/chrome/browser/ui/views/frame/browser_frame_view_win.cc
index dbc20cddf8adf..1e1f31a9ed0c4 100644
--- a/chrome/browser/ui/views/frame/browser_frame_view_win.cc
+++ b/chrome/browser/ui/views/frame/browser_frame_view_win.cc
@@ -12,6 +12,7 @@
 
 #include "base/trace_event/common/trace_event_common.h"
 #include "base/trace_event/trace_event.h"
+#include "base/win/windows_version.h"
 #include "chrome/app/chrome_command_ids.h"
 #include "chrome/app/chrome_dll_resource.h"
 #include "chrome/browser/themes/theme_properties.h"
@@ -191,6 +192,10 @@ bool BrowserFrameViewWin::HasVisibleBackgroundTabShapes(
     BrowserFrameActiveState active_state) const {
   DCHECK(GetWidget());
 
+  // Pre-Win 8, tabs never match the glass frame appearance.
+  if (base::win::GetVersion() < base::win::Version::WIN8)
+    return true;
+
   // Enabling high contrast mode disables the custom-drawn titlebar (so the
   // system-drawn frame will respect the native frame colors) and enables the
   // IncreasedContrastThemeSupplier (which does not respect the native frame
@@ -204,6 +209,15 @@ bool BrowserFrameViewWin::HasVisibleBackgroundTabShapes(
   return BrowserNonClientFrameView::HasVisibleBackgroundTabShapes(active_state);
 }
 
+bool BrowserFrameViewWin::CanDrawStrokes() const {
+  // On Win 7, the tabs are drawn as flat shapes against the glass frame, so
+  // the active tab always has a visible shape and strokes are unnecessary.
+  if (base::win::GetVersion() < base::win::Version::WIN8)
+    return false;
+
+  return BrowserNonClientFrameView::CanDrawStrokes();
+}
+
 SkColor BrowserFrameViewWin::GetCaptionColor(
     BrowserFrameActiveState active_state) const {
   return GetColorProvider()->GetColor(ShouldPaintAsActive(active_state)
@@ -342,39 +356,41 @@ int BrowserFrameViewWin::NonClientHitTest(const gfx::Point& point) {
     }
   }
 
-  // On Windows, the caption buttons are almost butted up to the top right
+  // On Windows 8+, the caption buttons are almost butted up to the top right
   // corner of the window. This code ensures the mouse isn't set to a size
   // cursor while hovering over the caption buttons, thus giving the incorrect
   // impression that the user can resize the window.
-  RECT button_bounds = {0};
-  if (SUCCEEDED(DwmGetWindowAttribute(views::HWNDForWidget(frame()),
-                                      DWMWA_CAPTION_BUTTON_BOUNDS,
-                                      &button_bounds, sizeof(button_bounds)))) {
-    gfx::RectF button_bounds_in_dips = gfx::ConvertRectToDips(
-        gfx::Rect(button_bounds), display::win::GetDPIScale());
-    // TODO(crbug.com/40150311): GetMirroredRect() requires an integer rect,
-    // but the size in DIPs may not be an integer with a fractional device
-    // scale factor. If we want to keep using integers, the choice to use
-    // ToFlooredRectDeprecated() seems to be doing the wrong thing given the
-    // comment below about insetting 1 DIP instead of 1 physical pixel. We
-    // should probably use ToEnclosedRect() and then we could have inset 1
-    // physical pixel here.
-    gfx::Rect buttons =
-        GetMirroredRect(gfx::ToFlooredRectDeprecated(button_bounds_in_dips));
-
-    // There is a small one-pixel strip right above the caption buttons in
-    // which the resize border "peeks" through.
-    constexpr int kCaptionButtonTopInset = 1;
-    // The sizing region at the window edge above the caption buttons is
-    // 1 px regardless of scale factor. If we inset by 1 before converting
-    // to DIPs, the precision loss might eliminate this region entirely. The
-    // best we can do is to inset after conversion. This guarantees we'll
-    // show the resize cursor when resizing is possible. The cost of which
-    // is also maybe showing it over the portion of the DIP that isn't the
-    // outermost pixel.
-    buttons.Inset(gfx::Insets::TLBR(kCaptionButtonTopInset, 0, 0, 0));
-    if (buttons.Contains(point)) {
-      return HTNOWHERE;
+  if (base::win::GetVersion() >= base::win::Version::WIN8) {
+    RECT button_bounds = {0};
+    if (SUCCEEDED(DwmGetWindowAttribute(views::HWNDForWidget(frame()),
+                                        DWMWA_CAPTION_BUTTON_BOUNDS,
+                                        &button_bounds,
+                                        sizeof(button_bounds)))) {
+      gfx::RectF button_bounds_in_dips = gfx::ConvertRectToDips(
+          gfx::Rect(button_bounds), display::win::GetDPIScale());
+      // TODO(crbug.com/1131681): GetMirroredRect() requires an integer rect,
+      // but the size in DIPs may not be an integer with a fractional device
+      // scale factor. If we want to keep using integers, the choice to use
+      // ToFlooredRectDeprecated() seems to be doing the wrong thing given the
+      // comment below about insetting 1 DIP instead of 1 physical pixel. We
+      // should probably use ToEnclosedRect() and then we could have inset 1
+      // physical pixel here.
+      gfx::Rect buttons =
+          GetMirroredRect(gfx::ToFlooredRectDeprecated(button_bounds_in_dips));
+
+      // There is a small one-pixel strip right above the caption buttons in
+      // which the resize border "peeks" through.
+      constexpr int kCaptionButtonTopInset = 1;
+      // The sizing region at the window edge above the caption buttons is
+      // 1 px regardless of scale factor. If we inset by 1 before converting
+      // to DIPs, the precision loss might eliminate this region entirely. The
+      // best we can do is to inset after conversion. This guarantees we'll
+      // show the resize cursor when resizing is possible. The cost of which
+      // is also maybe showing it over the portion of the DIP that isn't the
+      // outermost pixel.
+      buttons.Inset(gfx::Insets::TLBR(kCaptionButtonTopInset, 0, 0, 0));
+      if (buttons.Contains(point))
+        return HTNOWHERE;
     }
   }
 
diff --git a/chrome/browser/ui/views/frame/browser_frame_view_win.h b/chrome/browser/ui/views/frame/browser_frame_view_win.h
index fc9ab25369d8a..3ba633b58d812 100644
--- a/chrome/browser/ui/views/frame/browser_frame_view_win.h
+++ b/chrome/browser/ui/views/frame/browser_frame_view_win.h
@@ -42,6 +42,7 @@ class BrowserFrameViewWin : public BrowserNonClientFrameView,
   int GetTopInset(bool restored) const override;
   bool HasVisibleBackgroundTabShapes(
       BrowserFrameActiveState active_state) const override;
+  bool CanDrawStrokes() const override;
   SkColor GetCaptionColor(BrowserFrameActiveState active_state) const override;
   void UpdateThrobber(bool running) override;
   gfx::Size GetMinimumSize() const override;
diff --git a/chrome/browser/ui/views/frame/browser_view.cc b/chrome/browser/ui/views/frame/browser_view.cc
index ec249a76e75d0..e6deaa89bdcb0 100644
--- a/chrome/browser/ui/views/frame/browser_view.cc
+++ b/chrome/browser/ui/views/frame/browser_view.cc
@@ -323,6 +323,7 @@
 #endif
 
 #if BUILDFLAG(IS_WIN)
+#include "base/win/windows_version.h"
 #include "chrome/browser/taskbar/taskbar_decorator_win.h"
 #include "chrome/browser/win/jumplist.h"
 #include "chrome/browser/win/jumplist_factory.h"
@@ -1450,6 +1451,8 @@ bool BrowserView::IsOnCurrentWorkspace() const {
   return chromeos::DesksHelper::Get(native_win)
       ->BelongsToActiveDesk(native_win);
 #elif BUILDFLAG(IS_WIN)
+  if (base::win::GetVersion() < base::win::Version::WIN10)
+    return true;
   std::optional<bool> on_current_workspace =
       native_win->GetHost()->on_current_workspace();
   if (on_current_workspace.has_value())
diff --git a/chrome/browser/ui/views/frame/minimize_button_metrics_win.cc b/chrome/browser/ui/views/frame/minimize_button_metrics_win.cc
index 1e9aa01bc1db1..0a7154017bbb5 100644
--- a/chrome/browser/ui/views/frame/minimize_button_metrics_win.cc
+++ b/chrome/browser/ui/views/frame/minimize_button_metrics_win.cc
@@ -4,21 +4,36 @@
 
 #include "chrome/browser/ui/views/frame/minimize_button_metrics_win.h"
 
-#include <dwmapi.h>
-
 #include "base/check.h"
 #include "base/i18n/rtl.h"
+#include "base/win/windows_version.h"
+#include "dwmapi.h"
 #include "ui/base/win/shell.h"
 #include "ui/display/win/screen_win.h"
 #include "ui/gfx/geometry/point.h"
 
 namespace {
 
-const int kButtonBoundsPositionOffset = 6;
+// These constants were determined by manually adding various offsets
+// until the identity switcher was placed at the same location as before.
+// When a new or updated OS version is released, a new constant may need
+// to be added to this list and GetDefaultButtonBoundsOffset() is updated.
+const int kWin7ButtonBoundsPositionOffset = 1;
+const int kWin8ButtonBoundsPositionOffset = 10;
+const int kWin10ButtonBoundsPositionOffset = 6;
 const int kInvalidOffset = static_cast<int>(0x80000000);
 
+using base::win::GetVersion;
 using display::win::ScreenWin;
 
+int GetDefaultButtonBoundsOffset() {
+  if (GetVersion() >= base::win::Version::WIN10)
+    return kWin10ButtonBoundsPositionOffset;
+  if (GetVersion() >= base::win::Version::WIN8)
+    return kWin8ButtonBoundsPositionOffset;
+  return kWin7ButtonBoundsPositionOffset;
+}
+
 }  // namespace
 
 // static
@@ -27,9 +42,14 @@ int MinimizeButtonMetrics::last_cached_minimize_button_x_delta_ = 0;
 // static
 int MinimizeButtonMetrics::button_bounds_position_offset_ = kInvalidOffset;
 
-MinimizeButtonMetrics::MinimizeButtonMetrics() = default;
+MinimizeButtonMetrics::MinimizeButtonMetrics()
+    : hwnd_(nullptr),
+      cached_minimize_button_x_delta_(last_cached_minimize_button_x_delta_),
+      was_activated_(false) {
+}
 
-MinimizeButtonMetrics::~MinimizeButtonMetrics() = default;
+MinimizeButtonMetrics::~MinimizeButtonMetrics() {
+}
 
 void MinimizeButtonMetrics::Init(HWND hwnd) {
   DCHECK(!hwnd_);
@@ -58,18 +78,16 @@ int MinimizeButtonMetrics::GetButtonBoundsPositionOffset(
     const RECT& button_bounds,
     const RECT& window_bounds) const {
   if (button_bounds_position_offset_ == kInvalidOffset) {
-    if (!was_activated_ || !IsWindowVisible(hwnd_)) {
-      return kButtonBoundsPositionOffset;
-    }
+    if (!was_activated_ || !IsWindowVisible(hwnd_))
+      return GetDefaultButtonBoundsOffset();
     TITLEBARINFOEX info = {0};
     info.cbSize = sizeof(info);
     SendMessage(hwnd_, WM_GETTITLEBARINFOEX, 0,
                 reinterpret_cast<LPARAM>(&info));
     if (info.rgrect[2].right == info.rgrect[2].left ||
         (info.rgstate[2] & (STATE_SYSTEM_INVISIBLE | STATE_SYSTEM_OFFSCREEN |
-                            STATE_SYSTEM_UNAVAILABLE))) {
-      return kButtonBoundsPositionOffset;
-    }
+                            STATE_SYSTEM_UNAVAILABLE)))
+      return GetDefaultButtonBoundsOffset();
     button_bounds_position_offset_ =
         info.rgrect[2].left - (button_bounds.left + window_bounds.left);
   }
diff --git a/chrome/browser/ui/views/frame/minimize_button_metrics_win.h b/chrome/browser/ui/views/frame/minimize_button_metrics_win.h
index 651b7bf6099e1..c378b7e510fe2 100644
--- a/chrome/browser/ui/views/frame/minimize_button_metrics_win.h
+++ b/chrome/browser/ui/views/frame/minimize_button_metrics_win.h
@@ -43,15 +43,14 @@ class MinimizeButtonMetrics {
 
   int GetMinimizeButtonOffsetForWindow() const;
 
-  HWND hwnd_ = nullptr;
+  HWND hwnd_;
 
   // Cached offset of the minimize button. If RTL this is the location of the
   // minimize button, if LTR this is the offset from the right edge of the
   // client area to the minimize button.
-  mutable int cached_minimize_button_x_delta_ =
-      last_cached_minimize_button_x_delta_;
+  mutable int cached_minimize_button_x_delta_;
 
-  // Static cache of `cached_minimize_button_x_delta_`.
+  // Static cache of |cached_minimize_button_x_delta_|.
   static int last_cached_minimize_button_x_delta_;
 
   // Static cache of offset value representing the difference between
@@ -59,7 +58,7 @@ class MinimizeButtonMetrics {
   static int button_bounds_position_offset_;
 
   // Has OnHWNDActivated() been invoked?
-  bool was_activated_ = false;
+  bool was_activated_;
 };
 
 #endif  // CHROME_BROWSER_UI_VIEWS_FRAME_MINIMIZE_BUTTON_METRICS_WIN_H_
diff --git a/chrome/browser/ui/views/tabs/tab_strip.cc b/chrome/browser/ui/views/tabs/tab_strip.cc
index ed531bcb3e41c..75696411fed60 100644
--- a/chrome/browser/ui/views/tabs/tab_strip.cc
+++ b/chrome/browser/ui/views/tabs/tab_strip.cc
@@ -6,7 +6,6 @@
 
 #include <stddef.h>
 
-#include <algorithm>
 #include <iterator>
 #include <limits>
 #include <memory>
@@ -109,6 +108,7 @@
 #include "ui/views/window/non_client_view.h"
 
 #if BUILDFLAG(IS_WIN)
+#include "base/win/windows_version.h"
 #include "ui/display/win/screen_win.h"
 #include "ui/gfx/win/hwnd_util.h"
 #include "ui/views/win/hwnd_util.h"
@@ -2023,10 +2023,12 @@ bool TabStrip::ShouldHighlightCloseButtonAfterRemove() {
 
 bool TabStrip::TitlebarBackgroundIsTransparent() const {
 #if BUILDFLAG(IS_WIN)
-  return false;
-#else
+  // Windows 8+ uses transparent window contents (because the titlebar area is
+  // drawn by the system and not Chrome), but the actual titlebar is opaque.
+  if (base::win::GetVersion() >= base::win::Version::WIN8)
+    return false;
+#endif
   return GetWidget()->ShouldWindowContentsBeTransparent();
-#endif  // BUILDFLAG(IS_WIN)
 }
 
 int TabStrip::GetActiveTabWidth() const {
diff --git a/chrome/browser/ui/views/tooltip/tooltip_browsertest.cc b/chrome/browser/ui/views/tooltip/tooltip_browsertest.cc
index 02eb121db9339..2700bb7a9d2e0 100644
--- a/chrome/browser/ui/views/tooltip/tooltip_browsertest.cc
+++ b/chrome/browser/ui/views/tooltip/tooltip_browsertest.cc
@@ -6,6 +6,7 @@
 #include "base/run_loop.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/test/test_simple_task_runner.h"
+#include "base/win/windows_version.h"
 #include "build/build_config.h"
 #include "chrome/browser/ui/browser.h"
 #include "chrome/browser/ui/browser_commands.h"
@@ -190,6 +191,28 @@ class TooltipBrowserTest : public InProcessBrowserTest {
     return ChildFrameAt(web_contents_->GetPrimaryMainFrame(), index);
   }
 
+  bool SkipTestForOldWinVersion() const {
+#if BUILDFLAG(IS_WIN)
+    // On older Windows version, tooltips are displayed with TooltipWin instead
+    // of TooltipAura. For TooltipAura, a tooltip is displayed using a Widget
+    // and a Label and for TooltipWin, it is displayed using a native win32
+    // control. Since the observer we use in this class is the
+    // AnyWidgetObserver, we don't receive any update from non-Widget tooltips.
+    // This doesn't mean that no tooltip is displayed on older platforms, but
+    // that we are unable to execute the browser test successfully because the
+    // tooltip displayed is not displayed using a Widget.
+    //
+    // For now, we can simply skip the tests on older platforms, but it might be
+    // a good idea to eventually implement a custom observer (e.g.,
+    // TooltipStateObserver) that would work for both TooltipAura and
+    // TooltipWin, or remove once and for all TooltipWin. For more information
+    // on why we still need TooltipWin on Win7, see https://crbug.com/1201440.
+    if (base::win::GetVersion() <= base::win::Version::WIN7)
+      return true;
+#endif  // BUILDFLAG(IS_WIN)
+    return false;
+  }
+
   gfx::Point WebContentPositionToScreenCoordinate(int x, int y) {
     return gfx::Point(x, y) + rwhv_->GetViewBounds().OffsetFromOrigin();
   }
@@ -218,6 +241,9 @@ class TooltipBrowserTest : public InProcessBrowserTest {
 #endif
 IN_PROC_BROWSER_TEST_F(TooltipBrowserTest,
                        MAYBE_ShowTooltipFromWebContentWithCursor) {
+  if (SkipTestForOldWinVersion())
+    return;
+
   NavigateToURL("/tooltip.html");
   std::u16string expected_text = u"my tooltip";
 
@@ -252,6 +278,9 @@ IN_PROC_BROWSER_TEST_F(TooltipBrowserTest,
 #endif
 IN_PROC_BROWSER_TEST_F(TooltipBrowserTest,
                        MAYBE_ShowTooltipFromWebContentWithKeyboard) {
+  if (SkipTestForOldWinVersion())
+    return;
+
   NavigateToURL("/tooltip.html");
   std::u16string expected_text = u"my tooltip";
 
@@ -278,5 +307,8 @@ IN_PROC_BROWSER_TEST_F(TooltipBrowserTest,
 IN_PROC_BROWSER_TEST_F(TooltipBrowserTest,
                        DISABLED_ShowTooltipFromIFrameWithKeyboard) {
+  if (SkipTestForOldWinVersion())
+    return;
+
   // There are two tooltips in this file: one above the iframe and one inside
   // the iframe.
   NavigateToURL("/tooltip_in_iframe.html");
@@ -328,6 +360,9 @@ IN_PROC_BROWSER_TEST_F(TooltipBrowserTest,
 #endif
 IN_PROC_BROWSER_TEST_F(TooltipBrowserTest,
                        MAYBE_HideTooltipOnKeyPressTriggeredByCursor) {
+  if (SkipTestForOldWinVersion())
+    return;
+
   NavigateToURL("/tooltip.html");
   std::u16string expected_text = u"my tooltip";
 
@@ -364,6 +399,10 @@ IN_PROC_BROWSER_TEST_F(TooltipBrowserTest,
 #endif
 IN_PROC_BROWSER_TEST_F(TooltipBrowserTest,
                        MAYBE_HideTooltipOnKeyPressTriggeredByKeyboard) {
+  if (SkipTestForOldWinVersion()) {
+    return;
+  }
+
   NavigateToURL("/tooltip.html");
   std::u16string expected_text = u"my tooltip";
 
@@ -394,6 +433,9 @@ IN_PROC_BROWSER_TEST_F(TooltipBrowserTest,
 #endif
 IN_PROC_BROWSER_TEST_F(TooltipBrowserTest,
                        MAYBE_ScriptFocusHidesKeyboardTriggeredTooltip) {
+  if (SkipTestForOldWinVersion())
+    return;
+
   NavigateToURL("/tooltip_two_buttons.html");
   std::u16string expected_text_1 = u"my tooltip 1";
   std::u16string expected_text_2 = u"my tooltip 2";
diff --git a/chrome/browser/ui/views/touch_events_interactive_uitest_win.cc b/chrome/browser/ui/views/touch_events_interactive_uitest_win.cc
index b2e27441866d4..84613dce7ca26 100644
--- a/chrome/browser/ui/views/touch_events_interactive_uitest_win.cc
+++ b/chrome/browser/ui/views/touch_events_interactive_uitest_win.cc
@@ -4,6 +4,7 @@
 
 #include "base/memory/raw_ptr.h"
 #include "base/run_loop.h"
+#include "base/win/windows_version.h"
 #include "build/build_config.h"
 #include "chrome/browser/ui/views/test/view_event_test_base.h"
 #include "chrome/test/base/testing_profile.h"
@@ -161,6 +162,13 @@ class TouchEventsViewTest : public ViewEventTestBase {
   }
 
   void DoTestOnMessageLoop() override {
+    // ui_controls::SendTouchEvents which uses InjectTouchInput API only works
+    // on Windows 8 and up.
+    if (base::win::GetVersion() <= base::win::Version::WIN7) {
+      Done();
+      return;
+    }
+
     const int touch_pointer_count = 3;
     TouchEventHandler touch_event_handler;
     window()->GetNativeWindow()->GetHost()->window()->AddPreTargetHandler(
@@ -211,6 +219,13 @@ class TouchEventsRecursiveViewTest : public TouchEventsViewTest {
       delete;
 
   void DoTestOnMessageLoop() override {
+    // ui_controls::SendTouchEvents which uses InjectTouchInput API only works
+    // on Windows 8 and up.
+    if (base::win::GetVersion() <= base::win::Version::WIN7) {
+      Done();
+      return;
+    }
+
     const int touch_pointer_count = 1;
     TouchEventHandler touch_event_handler;
     window()->GetNativeWindow()->GetHost()->window()->AddPreTargetHandler(
diff --git a/chrome/browser/ui/webui/conflicts/conflicts_data_fetcher.cc b/chrome/browser/ui/webui/conflicts/conflicts_data_fetcher.cc
index a1e904f7004f4..f8342a344c72e 100644
--- a/chrome/browser/ui/webui/conflicts/conflicts_data_fetcher.cc
+++ b/chrome/browser/ui/webui/conflicts/conflicts_data_fetcher.cc
@@ -8,6 +8,7 @@
 #include <utility>
 
 #include "base/strings/string_util.h"
+#include "base/win/windows_version.h"
 #include "build/branding_buildflags.h"
 #include "chrome/browser/win/conflicts/module_database.h"
 #include "content/public/browser/browser_task_traits.h"
@@ -262,6 +263,10 @@ ThirdPartyFeaturesStatus GetThirdPartyFeaturesStatus(
     }
   }
 
+  // Figure out why the manager instance doesn't exist.
+  if (base::win::GetVersion() <= base::win::Version::WIN7)
+    return kNotAvailableWin7;
+
   if (!ModuleDatabase::IsThirdPartyBlockingPolicyEnabled())
     return kPolicyDisabled;
 
@@ -290,6 +295,9 @@ std::string GetThirdPartyFeaturesStatusString(ThirdPartyFeaturesStatus status) {
     case ThirdPartyFeaturesStatus::kPolicyDisabled:
       return "The ThirdPartyBlockingEnabled group policy is disabled.";
     case ThirdPartyFeaturesStatus::kFeatureDisabled:
+      if (base::win::GetVersion() < base::win::Version::WIN10)
+        return "The ThirdPartyModulesBlocking feature is disabled.";
+
       return "Both the IncompatibleApplicationsWarning and "
              "ThirdPartyModulesBlocking features are disabled.";
     case ThirdPartyFeaturesStatus::kModuleListInvalid:
@@ -297,12 +305,17 @@ std::string GetThirdPartyFeaturesStatusString(ThirdPartyFeaturesStatus status) {
     case ThirdPartyFeaturesStatus::kNoModuleListAvailable:
       return "Disabled - There is no Module List version available.";
     case ThirdPartyFeaturesStatus::kWarningInitialized:
+      DCHECK_GE(base::win::GetVersion(), base::win::Version::WIN10);
       return "The IncompatibleApplicationsWarning feature is enabled, while "
              "the ThirdPartyModulesBlocking feature is disabled.";
     case ThirdPartyFeaturesStatus::kBlockingInitialized:
+      if (base::win::GetVersion() < base::win::Version::WIN10)
+        return "The ThirdPartyModulesBlocking feature is enabled.";
+
       return "The ThirdPartyModulesBlocking feature is enabled, while the "
              "IncompatibleApplicationsWarning feature is disabled.";
     case ThirdPartyFeaturesStatus::kWarningAndBlockingInitialized:
+      DCHECK_GE(base::win::GetVersion(), base::win::Version::WIN10);
       return "Both the IncompatibleApplicationsWarning and "
              "ThirdPartyModulesBlocking features are enabled";
   }
@@ -460,7 +473,7 @@ void ConflictsDataFetcher::OnModuleDatabaseIdle() {
   ModuleDatabase::GetInstance()->RemoveObserver(this);
 
   base::Value::Dict results;
-  results.Set("moduleCount", static_cast<int>(module_list_->size()));
+  results.Set("moduleCount", int(module_list_->size()));
   results.Set("moduleList", std::move(*module_list_));
   module_list_ = std::nullopt;
 
diff --git a/chrome/browser/ui/webui/settings/settings_utils_win.cc b/chrome/browser/ui/webui/settings/settings_utils_win.cc
index c39f0509e7d3d..9a662c5006cd8 100644
--- a/chrome/browser/ui/webui/settings/settings_utils_win.cc
+++ b/chrome/browser/ui/webui/settings/settings_utils_win.cc
@@ -14,6 +14,7 @@
 #include "base/task/single_thread_task_runner.h"
 #include "base/task/thread_pool.h"
 #include "base/threading/thread.h"
+#include "base/win/windows_version.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/platform_util.h"
 #include "chrome/browser/profiles/profile.h"
@@ -30,7 +31,7 @@ namespace {
 // Shows a Windows certificate management dialog on the dialog thread.
 class ManageCertificatesDialog : public ui::BaseShellDialogImpl {
  public:
-  ManageCertificatesDialog() = default;
+  ManageCertificatesDialog() {}
 
   ManageCertificatesDialog(const ManageCertificatesDialog&) = delete;
   ManageCertificatesDialog& operator=(const ManageCertificatesDialog&) = delete;
@@ -102,9 +103,15 @@ void OpenConnectionDialogCallback() {
 }
 
 void ShowNetworkProxySettings(content::WebContents* /*web_contents*/) {
-  // See
-  // https://docs.microsoft.com/en-us/windows/uwp/launch-resume/launch-settings-app#network--internet
-  platform_util::OpenExternal(GURL("ms-settings:network-proxy"));
+  if (base::win::GetVersion() >= base::win::Version::WIN10) {
+    // See
+    // https://docs.microsoft.com/en-us/windows/uwp/launch-resume/launch-settings-app#network--internet
+    platform_util::OpenExternal(GURL("ms-settings:network-proxy"));
+  } else {
+    base::ThreadPool::PostTask(
+        FROM_HERE, {base::TaskPriority::USER_VISIBLE, base::MayBlock()},
+        base::BindOnce(&OpenConnectionDialogCallback));
+  }
 }
 
 void ShowManageSSLCertificates(content::WebContents* web_contents) {
diff --git a/chrome/browser/ui/webui/welcome/welcome_ui.cc b/chrome/browser/ui/webui/welcome/welcome_ui.cc
index 266ab44ddf4fa..5ab71e8fb36be 100644
--- a/chrome/browser/ui/webui/welcome/welcome_ui.cc
+++ b/chrome/browser/ui/webui/welcome/welcome_ui.cc
@@ -30,6 +30,10 @@
 #include "net/base/url_util.h"
 #include "ui/base/webui/web_ui_util.h"
 
+#if BUILDFLAG(IS_WIN)
+#include "base/win/windows_version.h"
+#endif
+
 namespace {
 
 const char kPreviewBackgroundPath[] = "preview-background.jpg";
@@ -141,7 +145,8 @@ WelcomeUI::WelcomeUI(content::WebUI* web_ui, const GURL& url)
 #endif
 
 #if BUILDFLAG(IS_WIN)
-  html_source->AddBoolean("is_win10", true);
+  html_source->AddBoolean("is_win10",
+                          base::win::GetVersion() >= base::win::Version::WIN10);
 #endif
 
   // Add the shared bookmark handler for welcome modules.