Fix black background when locking with fullscreen window:

ui/base/animation/animation_container.h

Index: ui/base/animation/animation_container.h
diff --git a/ui/base/animation/animation_container.h b/ui/base/animation/animation_container.h
index 89f6392392402fbc8151fb4165d5e59c366d86ac..ad4d7a94361ab017b9ee7d4fcff2750ba58e98b5 100644
--- a/ui/base/animation/animation_container.h
+++ b/ui/base/animation/animation_container.h
@@ -17,6 +17,10 @@ namespace ui {
 class AnimationContainerElement;
 class AnimationContainerObserver;
 
+namespace test {
+class AnimationContainerTestHelper;
+}
+
 // AnimationContainer is used by Animation to manage the underlying timer.
 // Internally each Animation creates a single AnimationContainer. You can
 // group a set of Animations into the same AnimationContainer by way of
@@ -41,6 +45,9 @@ class UI_EXPORT AnimationContainer
   // directly.
   void Stop(AnimationContainerElement* animation);
 
+  // Returns current time.
+  base::TimeTicks GetCurrentTime();
+
   void set_observer(AnimationContainerObserver* observer) {
     observer_ = observer;
   }
@@ -53,6 +60,7 @@ class UI_EXPORT AnimationContainer
 
  private:
   friend class base::RefCounted<AnimationContainer>;
+  friend class test::AnimationContainerTestHelper;
 
   typedef std::set<AnimationContainerElement*> Elements;
 
@@ -83,6 +91,13 @@ class UI_EXPORT AnimationContainer
 
   AnimationContainerObserver* observer_;
 
+  // Used for testing : indicates that "Time" is controlled by
+  // AnimationContainerTestHelper.
+  bool test_timing_enabled_;
+
+  // Current time for tests.
+  base::TimeTicks test_time_;
+
   DISALLOW_COPY_AND_ASSIGN(AnimationContainer);
 };