Always use default theme for System App popup settings pages

Terminal System App uses an almost black (#101010) theme
by default for the main tabbed window.  However, UX
have requested that the settings page always use white
for the frame, similar to OS settings.

Screenshots:
old: crbug.com/1033339#c7
new: crbug.com/1033339#c19

Since both windows are part of the same app, and it is not
possible to have a manifest with 2 different themes
specified, we will control the theme for
System App TYPE_APP_POPUP to always use default which
is white for light-mode, and something suitable
for dark-mode.

Fix for BrowserNonClientFrameViewMac which had not yet been
updated to support browser TYPE_APP_POPUP as revealed by
the included test.

Bug: 1033339
Change-Id: I7b0d7cc291e5f5895ddfda2ad384256c3519d0a8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2066378
Commit-Queue: Joel Hockey <joelhockey@chromium.org>
Reviewed-by: Peter Kasting <pkasting@chromium.org>
Cr-Commit-Position: refs/heads/master@{#743852}

chrome/browser/ui/views/frame/browser_non_client_frame_view_mac.mm

@@ -77,10 +77,11 @@ BrowserNonClientFrameViewMac::BrowserNonClientFrameViewMac(
     // The window title appears above the web app frame toolbar (if present),
     // which surrounds the title with minimal-ui buttons on the left,
     // and other controls (such as the app menu button) on the right.
-    DCHECK(browser_view->ShouldShowWindowTitle());
-    window_title_ = AddChildView(
-        std::make_unique<views::Label>(browser_view->GetWindowTitle()));
-    window_title_->SetID(VIEW_ID_WINDOW_TITLE);
+    if (browser_view->ShouldShowWindowTitle()) {
+      window_title_ = AddChildView(
+          std::make_unique<views::Label>(browser_view->GetWindowTitle()));
+      window_title_->SetID(VIEW_ID_WINDOW_TITLE);
+    }
   }
 }
 

chrome/browser/ui/web_applications/app_browser_controller_browsertest.cc

@@ -101,6 +101,16 @@ class AppBrowserControllerBrowserTest : public InProcessBrowserTest {
         tabbed_app_url_));
   }
 
+  void InstallAndLaunchMockPopup() {
+    test_system_web_app_installation_->WaitForAppInstall();
+    auto params = web_app::CreateSystemWebAppLaunchParams(
+        browser()->profile(), test_system_web_app_installation_->GetType());
+    params->disposition = WindowOpenDisposition::NEW_POPUP;
+    app_browser_ = web_app::LaunchSystemWebApp(
+        browser()->profile(), test_system_web_app_installation_->GetType(),
+        test_system_web_app_installation_->GetAppUrl(), *params);
+  }
+
   GURL GetActiveTabURL() {
     return app_browser_->tab_strip_model()
         ->GetActiveWebContents()
@@ -188,4 +198,10 @@ IN_PROC_BROWSER_TEST_F(AppBrowserControllerBrowserTest, TabLoadNoThemeChange) {
   EXPECT_EQ(GetTabColor(app_browser_), SK_ColorGREEN);
 }
 
+IN_PROC_BROWSER_TEST_F(AppBrowserControllerBrowserTest,
+                       WhiteThemeForSystemAppPopup) {
+  InstallAndLaunchMockPopup();
+  EXPECT_FALSE(app_browser_->app_controller()->GetThemeColor().has_value());
+}
+
 }  // namespace web_app

chrome/browser/ui/web_applications/web_app_browser_controller.cc

@@ -73,6 +73,10 @@ gfx::ImageSkia WebAppBrowserController::GetWindowIcon() const {
 }
 
 base::Optional<SkColor> WebAppBrowserController::GetThemeColor() const {
+  // System App popups (settings pages) always use default theme.
+  if (is_for_system_web_app() && browser()->is_type_app_popup())
+    return base::nullopt;
+
   base::Optional<SkColor> web_theme_color =
       AppBrowserController::GetThemeColor();
   if (web_theme_color)