cc: Plumb group id through animation creation and start/finish notifications

cc/blink/web_animation_impl.cc

 // 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.
 
 #include "cc/blink/web_animation_impl.h"
 
 #include "cc/animation/animation.h"
 #include "cc/animation/animation_curve.h"
 #include "cc/animation/animation_id_provider.h"
 #include "cc/blink/web_filter_animation_curve_impl.h"
@@ skipping 55 matching lines @@
       static_cast<cc::Animation::TargetProperty>(target_property));
 }
 
 WebCompositorAnimationImpl::~WebCompositorAnimationImpl() {
 }
 
 int WebCompositorAnimationImpl::id() {
   return animation_->id();
 }
 
+int WebCompositorAnimationImpl::group() {
+  return animation_->group();
+}
+
 blink::WebCompositorAnimation::TargetProperty
 WebCompositorAnimationImpl::targetProperty() const {
   return static_cast<WebCompositorAnimationImpl::TargetProperty>(
       animation_->target_property());
 }
 
 double WebCompositorAnimationImpl::iterations() const {
   return animation_->iterations();
 }
 
@@ skipping 101 matching lines @@
       break;
   }
 }
 
 scoped_ptr<cc::Animation> WebCompositorAnimationImpl::PassAnimation() {
   animation_->set_needs_synchronized_start_time(true);
   return animation_.Pass();
 }
 
 }  // namespace cc_blink