Fix black background when locking with fullscreen window:

ui/compositor/layer_animator.cc

Index: ui/compositor/layer_animator.cc
diff --git a/ui/compositor/layer_animator.cc b/ui/compositor/layer_animator.cc
index 98261fe539e1e287eb62f6cedcd082f70cc12c8a..72fd3d46e0bf3f1b27da722c6a4e006af5b9c8cb 100644
--- a/ui/compositor/layer_animator.cc
+++ b/ui/compositor/layer_animator.cc
@@ -86,6 +86,14 @@ LayerAnimator* LayerAnimator::CreateImplicitAnimator() {
       base::TimeDelta::FromMilliseconds(kDefaultTransitionDurationMs));
 }
 
+// static
+scoped_ptr<test::AnimationContainerTestHelper>
+LayerAnimator::CreateAnimatorHelperForTest() {
+  scoped_ptr<test::AnimationContainerTestHelper> result;
+  result.reset(new test::AnimationContainerTestHelper(GetAnimationContainer()));
+  return result.Pass();
+}
+
 // This macro provides the implementation for the setter and getter (well,
 // the getter of the target value) for an animated property. For example,
 // it is used for the implementations of SetTransform and GetTargetTransform.