Revert 152059 - Gradient overlay for constrained window

ui/base/animation/linear_animation.h

Index: ui/base/animation/linear_animation.h
===================================================================
--- ui/base/animation/linear_animation.h	(revision 152061)
+++ ui/base/animation/linear_animation.h	(working copy)
@@ -32,9 +32,6 @@
   // can override this to provide others.
   virtual double GetCurrentValue() const OVERRIDE;
 
-  // Change the current state of the animation to |new_value|.
-  void SetCurrentValue(double new_value);
-
   // Skip to the end of the current animation.
   void End();
 
@@ -45,16 +42,13 @@
  protected:
   // Called when the animation progresses. Subclasses override this to
   // efficiently update their state.
-  virtual void AnimateToState(double state) {}
+  virtual void AnimateToState(double state) = 0;
 
   // Invoked by the AnimationContainer when the animation is running to advance
   // the animation. Use |time_now| rather than Time::Now to avoid multiple
   // animations running at the same time diverging.
   virtual void Step(base::TimeTicks time_now) OVERRIDE;
 
-  // Overriden to initialize state.
-  virtual void AnimationStarted() OVERRIDE;
-
   // Overriden to advance to the end (if End was invoked).
   virtual void AnimationStopped() OVERRIDE;