CustomButton: restrict animation repaints to buttons that actually animate

ui/views/controls/button/custom_button.h

Index: ui/views/controls/button/custom_button.h
diff --git a/ui/views/controls/button/custom_button.h b/ui/views/controls/button/custom_button.h
index a73d5008cf67e90ce6790de0f9bca7660573736c..87ae0671de860c57c73e4dc47d89d9d342e750c8 100644
--- a/ui/views/controls/button/custom_button.h
+++ b/ui/views/controls/button/custom_button.h
@@ -152,6 +152,9 @@ class VIEWS_EXPORT CustomButton : public Button, public gfx::AnimationDelegate {
   // state). This does not take into account enabled state.
   bool ShouldEnterHoveredState();
 
+  void set_animates_hover(bool animates) { animates_hover_ = animates; }
+  bool animates_hover() { return animates_hover_; }
+
   // Overridden from Button:
   void NotifyClick(const ui::Event& event) override;
   void OnClickCanceled(const ui::Event& event) override;
@@ -191,6 +194,11 @@ class VIEWS_EXPORT CustomButton : public Button, public gfx::AnimationDelegate {
   // The color of the ripple and hover.
   SkColor ink_drop_base_color_;
 
+  // Whether this button has a hover effect. If this returns true, painting the

[sky, 2016/10/11 19:17:45]

As you mentioned previously, it seems wrong that an animation would be started
and nothing visually changes. This makes me question the usefullness of having
CustomButton have the animation. Is it possible to move the animation entirely
to the subclass? What class is starting an animation but has no visual change
when the animation ticks?

+  // button is taken to be dependent on the animation state and SchedulePaint()
+  // is called as the hover animation progresses.
+  bool animates_hover_ = false;
+
   DISALLOW_COPY_AND_ASSIGN(CustomButton);
 };