cc: Support animating scroll offset

cc/test/animation_test_common.cc

Index: cc/test/animation_test_common.cc
diff --git a/cc/test/animation_test_common.cc b/cc/test/animation_test_common.cc
index 7ab26a5d8b548500392d6acf9b21ae4b0c8e0bf6..e6c67736c275c5502d41c8ed3094fbe0457cea07 100644
--- a/cc/test/animation_test_common.cc
+++ b/cc/test/animation_test_common.cc
@@ -205,6 +205,11 @@ void FakeLayerAnimationValueObserver::OnTransformAnimated(
   transform_ = transform;
 }
 
+void FakeLayerAnimationValueObserver::OnScrollOffsetAnimated(
+    gfx::Vector2dF scroll_offset) {
+  scroll_offset_ = scroll_offset;
+}
+
 void FakeLayerAnimationValueObserver::OnAnimationWaitingForDeletion() {
   animation_waiting_for_deletion_ = true;
 }
@@ -217,6 +222,11 @@ bool FakeInactiveLayerAnimationValueObserver::IsActive() const {
   return false;
 }
 
+gfx::Vector2dF FakeLayerAnimationValueProvider::ScrollOffsetForAnimation()
+    const {
+  return scroll_offset_;
+}
+
 scoped_ptr<cc::AnimationCurve> FakeFloatTransition::Clone() const {
   return make_scoped_ptr(
       new FakeFloatTransition(*this)).PassAs<cc::AnimationCurve>();