dark_mode: Make system tray's background color can be live updated.

Bug: 1131543
Change-Id: I9c1cb61c48033625ecdc0f05e5188ab1ac2e7783
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2454389
Commit-Queue: Min Chen <minch@chromium.org>
Reviewed-by: Ahmed Fakhry <afakhry@chromium.org>
Reviewed-by: Xiaoqian Dai <xdai@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#815381}

ash/style/ash_color_provider.cc

@@ -71,6 +71,12 @@ void AttemptRestartChrome() {
   Shell::Get()->session_controller()->AttemptRestartChrome();
 }
 
+// AshColorProvider is kind of NativeTheme of ChromeOS. This will notify the
+// View::OnThemeChanged to live update the colors on color mode/theme changes.
+void NotifyThemeChanges() {
+  ui::NativeTheme::GetInstanceForNativeUi()->NotifyObservers();
+}
+
 }  // namespace
 
 AshColorProvider::AshColorProvider() {
@@ -406,12 +412,16 @@ void AshColorProvider::NotifyDarkModeEnabledPrefChange() {
   const bool is_enabled = IsDarkModeEnabled();
   for (auto& observer : observers_)
     observer.OnColorModeChanged(is_enabled);
+
+  NotifyThemeChanges();
 }
 
 void AshColorProvider::NotifyColorModeThemedPrefChange() {
   const bool is_themed = IsThemed();
   for (auto& observer : observers_)
     observer.OnColorModeThemed(is_themed);
+
+  NotifyThemeChanges();
 }
 
 }  // namespace ash

ash/system/tray/tray_bubble_view.cc

@@ -248,8 +248,6 @@ TrayBubbleView::TrayBubbleView(const InitParams& init_params)
 
     layer()->SetRoundedCornerRadius(
         gfx::RoundedCornersF{kUnifiedTrayCornerRadius});
-    layer()->SetColor(AshColorProvider::Get()->GetBaseLayerColor(
-        AshColorProvider::BaseLayerType::kTransparent80));
     layer()->SetFillsBoundsOpaquely(false);
     layer()->SetIsFastRoundedCorner(true);
     layer()->SetBackgroundBlur(kUnifiedMenuBackgroundBlur);
@@ -469,6 +467,15 @@ const char* TrayBubbleView::GetClassName() const {
   return "TrayBubbleView";
 }
 
+void TrayBubbleView::OnThemeChanged() {
+  views::BubbleDialogDelegateView::OnThemeChanged();
+  DCHECK(layer());
+  if (layer()->type() != ui::LAYER_SOLID_COLOR)
+    return;
+  layer()->SetColor(AshColorProvider::Get()->GetBaseLayerColor(
+      AshColorProvider::BaseLayerType::kTransparent80));
+}
+
 void TrayBubbleView::MouseMovedOutOfHost() {
   // The user moved the mouse that was over the bubble when it was first shown.
   if (delegate_)

ash/system/tray/tray_bubble_view.h

@@ -152,36 +152,37 @@ class ASH_EXPORT TrayBubbleView : public views::BubbleDialogDelegateView,
   void set_gesture_dragging(bool dragging) { is_gesture_dragging_ = dragging; }
   bool is_gesture_dragging() const { return is_gesture_dragging_; }
 
-  // Overridden from views::WidgetDelegate.
+  // views::WidgetDelegate:
   std::unique_ptr<views::NonClientFrameView> CreateNonClientFrameView(
       views::Widget* widget) override;
   bool WidgetHasHitTestMask() const override;
   void GetWidgetHitTestMask(SkPath* mask) const override;
   base::string16 GetAccessibleWindowTitle() const override;
 
-  // Overridden from views::BubbleDialogDelegateView.
+  // views::BubbleDialogDelegateView:
   void OnBeforeBubbleWidgetInit(views::Widget::InitParams* params,
                                 views::Widget* bubble_widget) const override;
   void OnWidgetClosing(views::Widget* widget) override;
   void OnWidgetActivationChanged(views::Widget* widget, bool active) override;
   ui::LayerType GetLayerType() const override;
 
-  // Overridden from views::View.
+  // views::View:
   gfx::Size CalculatePreferredSize() const override;
   int GetHeightForWidth(int width) const override;
   void OnMouseEntered(const ui::MouseEvent& event) override;
   void OnMouseExited(const ui::MouseEvent& event) override;
   void GetAccessibleNodeData(ui::AXNodeData* node_data) override;
   const char* GetClassName() const override;
+  void OnThemeChanged() override;
 
-  // Overridden from MouseWatcherListener
+  // views::MouseWatcherListener:
   void MouseMovedOutOfHost() override;
 
  protected:
-  // Overridden from views::BubbleDialogDelegateView.
+  // views::BubbleDialogDelegateView:
   ax::mojom::Role GetAccessibleWindowRole() override;
 
-  // Overridden from views::View.
+  // views::View:
   void ChildPreferredSizeChanged(View* child) override;
 
   // Changes the insets from the bubble border. These were initially set using