Reland "Fix GTK+ themed web app windows using incorrect window title color"

This is a reland of 61579f7a
The original CL was optimisic that all linux bots used the same
system theme colors.
This is not the case for Linux MSan Tests:
https://logs.chromium.org/logs/chromium/buildbucket/cr-buildbucket.appspot.com/8877850460224985872/+/steps/browser_tests/0/logs/Deterministic_failure:_WebAppOpaqueBrowserFrameViewTest.SystemThemeColor__status_FAILURE_/0
This revised CL loosens the expectations to allow for any light title
bar color.

Original change's description:
> Fix GTK+ themed web app windows using incorrect window title color
>
> This CL fixes a bug where web app windows on Linux with GTK+ themes set
> would use system colors for the title bar but web app colors for the text.
> This sometimes resulted in unreadable contrast levels.
>
> Before: https://bugs.chromium.org/p/chromium/issues/attachment?aid=450694&signed_aid=ojOLuOeFlvGsonFz7D8lkA==&inline=1
> After: https://bugs.chromium.org/p/chromium/issues/attachment?aid=450693&signed_aid=CN1FqbV6S5JWEJfOW5L4oQ==&inline=1
>
> Bug: 1087693
> Change-Id: Ifc408c4c1fb1c6cae4014f806248a05f5e2f617f
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2239769
> Commit-Queue: Alan Cutter <alancutter@chromium.org>
> Reviewed-by: Bret Sepulveda <bsep@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#776994}

Bug: 1087693
Change-Id: I3f924f2976114f8bfe58e8a230a036eed9b0df0d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2239912Reviewed-by: Peter Kasting <pkasting@chromium.org>
Commit-Queue: Peter Kasting <pkasting@chromium.org>
Auto-Submit: Alan Cutter <alancutter@chromium.org>
Cr-Commit-Position: refs/heads/master@{#777271}

chrome/browser/ui/views/frame/browser_frame.cc

@@ -202,7 +202,7 @@ bool BrowserFrame::GetAccelerator(int command_id,
 
 const ui::ThemeProvider* BrowserFrame::GetThemeProvider() const {
   Browser* browser = browser_view_->browser();
-  if (browser->app_controller())
+  if (browser->app_controller() && !IsUsingGtkTheme(browser->profile()))
     return browser->app_controller()->GetThemeProvider();
   return &ThemeService::GetThemeProviderForProfile(browser->profile());
 }

chrome/browser/ui/views/frame/opaque_browser_frame_view_browsertest.cc

@@ -17,6 +17,7 @@
 #include "chrome/common/web_application_info.h"
 #include "chrome/test/base/in_process_browser_test.h"
 #include "content/public/test/browser_test.h"
+#include "ui/gfx/color_utils.h"
 #include "ui/views/test/test_views.h"
 
 // Tests web-app windows that use the OpaqueBrowserFrameView implementation
@@ -104,13 +105,35 @@ IN_PROC_BROWSER_TEST_F(WebAppOpaqueBrowserFrameViewTest, NoThemeColor) {
 }
 
 #if defined(OS_LINUX) && !defined(OS_CHROMEOS)
+// The app theme color should be ignored in system theme mode.
 IN_PROC_BROWSER_TEST_F(WebAppOpaqueBrowserFrameViewTest, SystemThemeColor) {
   SetThemeMode(ThemeMode::kSystem);
-  // The color here should be ignored in system mode.
-  ASSERT_TRUE(InstallAndLaunchWebApp(SK_ColorRED));
 
+  // Read unthemed native frame color.
+  SkColor native_frame_color =
+      BrowserView::GetBrowserViewForBrowser(browser())
+          ->frame()
+          ->GetFrameView()
+          ->GetFrameColor(BrowserFrameActiveState::kActive);
+  SkColor expected_caption_color =
+      color_utils::GetColorWithMaxContrast(native_frame_color);
+
+  // Install web app with theme color contrasting against native frame color.
+  SkColor theme_color =
+      color_utils::GetColorWithMaxContrast(native_frame_color);
+  EXPECT_NE(color_utils::IsDark(theme_color),
+            color_utils::IsDark(native_frame_color));
+  ASSERT_TRUE(InstallAndLaunchWebApp(theme_color));
+
+  // App theme color should be ignored in favor of native system theme.
+  EXPECT_EQ(opaque_browser_frame_view_->GetFrameColor(
+                BrowserFrameActiveState::kActive),
+            native_frame_color);
+  EXPECT_EQ(opaque_browser_frame_view_->GetCaptionColor(
+                BrowserFrameActiveState::kActive),
+            expected_caption_color);
   EXPECT_EQ(web_app_frame_toolbar_->active_color_for_testing(),
-            gfx::kGoogleGrey900);
+            expected_caption_color);
 }
 #endif  // defined(OS_LINUX) && !defined(OS_CHROMEOS)