Made the CompositorAnimationObserver class usable

chrome/browser/chromeos/ui/accessibility_focus_ring_controller.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_CHROMEOS_UI_ACCESSIBILITY_FOCUS_RING_CONTROLLER_H_
 #define CHROME_BROWSER_CHROMEOS_UI_ACCESSIBILITY_FOCUS_RING_CONTROLLER_H_
 
 #include <vector>
 
 #include "base/basictypes.h"
@@ skipping 36 matching lines @@
                     std::vector<AccessibilityFocusRing>* rings) const;
 
   virtual int GetMargin() const;
 
  private:
   // FocusRingLayerDelegate.
   void OnDeviceScaleFactorChanged() override;
 
   // CompositorAnimationObserver.
   void OnAnimationStep(base::TimeTicks timestamp) override;
+  void OnCompositingShuttingDown(ui::Compositor* compositor) override;
 
   void Update();
 
   AccessibilityFocusRing RingFromSortedRects(
       const std::vector<gfx::Rect>& rects) const;
   void SplitIntoParagraphShape(
       const std::vector<gfx::Rect>& rects,
       gfx::Rect* top,
       gfx::Rect* middle,
       gfx::Rect* bottom) const;
   bool Intersects(const gfx::Rect& r1, const gfx::Rect& r2) const;
 
   std::vector<gfx::Rect> rects_;
   std::vector<AccessibilityFocusRing> previous_rings_;
   std::vector<AccessibilityFocusRing> rings_;
   ScopedVector<AccessibilityFocusRingLayer> layers_;
   base::TimeTicks focus_change_time_;
   ui::Compositor* compositor_;
 
   friend struct DefaultSingletonTraits<AccessibilityFocusRingController>;
 
   DISALLOW_COPY_AND_ASSIGN(AccessibilityFocusRingController);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_UI_ACCESSIBILITY_FOCUS_RING_CONTROLLER_H_