Remove ScrollableArea::GetFrameViewBase and move ScheduleAnimation into subclasses.

third_party/WebKit/Source/platform/scroll/ScrollableArea.h

Index: third_party/WebKit/Source/platform/scroll/ScrollableArea.h
diff --git a/third_party/WebKit/Source/platform/scroll/ScrollableArea.h b/third_party/WebKit/Source/platform/scroll/ScrollableArea.h
index eaa0172ec6fde8fffbea30891128ca7eafac410f..b2e951eb5af5700be1fa892d56a89c09673e6bfa 100644
--- a/third_party/WebKit/Source/platform/scroll/ScrollableArea.h
+++ b/third_party/WebKit/Source/platform/scroll/ScrollableArea.h
@@ -261,7 +261,7 @@ class PLATFORM_EXPORT ScrollableArea : public GarbageCollectedMixin,
 
   // Let subclasses provide a way of asking for and servicing scroll
   // animations.
-  virtual bool ScheduleAnimation();
+  virtual bool ScheduleAnimation() { return false; }
   virtual void ServiceScrollAnimations(double monotonic_time);
   virtual void UpdateCompositorScrollAnimations();
   virtual void RegisterForAnimation() {}
@@ -341,9 +341,6 @@ class PLATFORM_EXPORT ScrollableArea : public GarbageCollectedMixin,
   virtual int HorizontalScrollbarHeight(
       OverlayScrollbarClipBehavior = kIgnorePlatformOverlayScrollbarSize) const;
 
-  // Returns the widget associated with this ScrollableArea.
-  virtual FrameViewBase* GetFrameViewBase() { return nullptr; }
-
   virtual LayoutBox* GetLayoutBox() const { return nullptr; }
 
   // Maps a quad from the coordinate system of a LayoutObject contained by the