cc: Split animating and drawing into separate actions

cc/animation/layer_animation_controller.cc

 // Copyright 2012 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/animation/layer_animation_controller.h"
 
 #include <algorithm>
 
 #include "cc/animation/animation.h"
 #include "cc/animation/animation_delegate.h"
@@ skipping 187 matching lines @@
         NOTREACHED();
     }
   }
 }
 
 void LayerAnimationController::UpdateState(bool start_ready_animations,
                                            AnimationEventsVector* events) {
   if (!HasActiveValueObserver())
     return;
 
+  DCHECK(last_tick_time_);
   if (start_ready_animations)
     PromoteStartedAnimations(last_tick_time_, events);
 
   MarkFinishedAnimations(last_tick_time_);
   MarkAnimationsForDeletion(last_tick_time_, events);
 
   if (start_ready_animations) {
     StartAnimations(last_tick_time_);
     PromoteStartedAnimations(last_tick_time_, events);
   }
@@ skipping 654 matching lines @@
         value_observers_);
     LayerAnimationValueObserver* obs;
     while ((obs = it.GetNext()) != NULL)
       if (obs->IsActive())
         return true;
   }
   return false;
 }
 
 }  // namespace cc