Ensure that the focus ring in the bookmarks bar does not paint outside the parent view.

ui/views/controls/scroll_view.h

Index: ui/views/controls/scroll_view.h
diff --git a/ui/views/controls/scroll_view.h b/ui/views/controls/scroll_view.h
index af9111a05cae1a2dd25daba64afe629560c7751e..5b7f1f7432f08b6e9878aa8b38fc36ae5bd2c569 100644
--- a/ui/views/controls/scroll_view.h
+++ b/ui/views/controls/scroll_view.h
@@ -56,6 +56,8 @@ class VIEWS_EXPORT ScrollView : public View, public ScrollBarController {
   const View* contents() const { return contents_; }
   View* contents() { return contents_; }
 
+  const View* contents_viewport() const { return contents_viewport_; }

[sky, 2017/04/18 15:35:48]

I would prefer not to expose this. Can you friend the test?

[ananta, 2017/04/18 22:22:39]

Done.

+
   // Sets the header, deleting the previous header.
   void SetHeader(View* header);
 
@@ -105,6 +107,9 @@ class VIEWS_EXPORT ScrollView : public View, public ScrollBarController {
   void OnGestureEvent(ui::GestureEvent* event) override;
   const char* GetClassName() const override;
   void OnNativeThemeChanged(const ui::NativeTheme* theme) override;
+  void ViewHierarchyChanged(
+      const ViewHierarchyChangedDetails& details) override;
+  void OnChildLayerChanged(View* child) override;
 
   // ScrollBarController overrides:
   void ScrollToPosition(ScrollBar* source, int position) override;
@@ -162,6 +167,11 @@ class VIEWS_EXPORT ScrollView : public View, public ScrollBarController {
   void AddBorder();
   void UpdateBorder();
 
+  // Enables view port layering if layering is enabled for the |child| or any

[sky, 2017/04/18 15:35:47]

'layering is enabled' -> |child| has a layer

[ananta, 2017/04/18 22:22:39]

Done.

+  // of its descendants. Returns true if yes. We short circuit the recursion
+  // if we enabled layering.
+  bool EnableLayeringRecursivelyForChild(View* child);
+
   // The current contents and its viewport. |contents_| is contained in
   // |contents_viewport_|.
   View* contents_;
@@ -204,6 +214,12 @@ class VIEWS_EXPORT ScrollView : public View, public ScrollBarController {
   // Focus ring, if one is installed.
   View* focus_ring_ = nullptr;
 
+  // Set to true if we enabled layering for the viewport.
+  bool viewport_layer_enabled_ = false;
+
+  // Set to true if the scroll with layers feature is enabled.
+  bool scroll_with_layers_enabled_ = false;

[sky, 2017/04/18 15:35:47]

Make const

[ananta, 2017/04/18 22:22:39]

We cannot do that as this is set based on the experiment.

[sky, 2017/04/19 00:03:04]

If you move scroll_with_layers_enabled_ =
       base::FeatureList::IsEnabled(kToolkitViewsScrollWithLayers);

to the member initializer can't it be const?

[ananta, 2017/04/19 00:53:17]

Thanks. done

+
   DISALLOW_COPY_AND_ASSIGN(ScrollView);
 };