cc: Make PictureLayerImpl use a better choice for animated raster scale.

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 <vector>
 
 #include "cc/animation/animation.h"
 #include "cc/animation/animation_delegate.h"
 #include "cc/animation/animation_registrar.h"
 #include "cc/animation/keyframed_animation_curve.h"
 #include "cc/animation/layer_animation_value_observer.h"
 #include "cc/animation/layer_animation_value_provider.h"
 #include "cc/animation/scroll_offset_animation_curve.h"
 #include "cc/base/scoped_ptr_algorithm.h"
 #include "cc/output/filter_operations.h"
@@ skipping 469 matching lines @@
 
     const TransformAnimationCurve* transform_animation_curve =
         animations_[i]->curve()->ToTransformAnimationCurve();
     if (!transform_animation_curve->IsTranslation())
       return false;
   }
 
   return true;
 }
 
-bool LayerAnimationController::MaximumScale(float* max_scale) const {
+bool LayerAnimationController::MaximumTargetScale(float* max_scale) const {
   *max_scale = 0.f;
   for (size_t i = 0; i < animations_.size(); ++i) {
     if (animations_[i]->is_finished() ||
         animations_[i]->target_property() != Animation::Transform)
       continue;
 
     const TransformAnimationCurve* transform_animation_curve =
         animations_[i]->curve()->ToTransformAnimationCurve();

[ajuma, 2014/10/10 13:43:07]

We also need to account for animations being run in reverse (which would be
those with Reverse or AlternateReverse direction and positive playback rate, and
those with Normal or Alternate direction and negative playback rate), since that
changes the targets to consider (the endpoint of the last keyframe is the real
starting point).

[danakj, 2014/10/10 15:14:45]

OK I think I have this now, thanks!

     float animation_scale = 0.f;
-    if (!transform_animation_curve->MaximumScale(&animation_scale))
+    if (!transform_animation_curve->MaximumTargetScale(&animation_scale))
       return false;
     *max_scale = std::max(*max_scale, animation_scale);
   }
 
   return true;
 }
 
 void LayerAnimationController::PushNewAnimationsToImplThread(
     LayerAnimationController* controller_impl) const {
   // Any new animations owned by the main thread's controller are cloned and
@@ skipping 496 matching lines @@
         value_observers_);
     LayerAnimationValueObserver* obs;
     while ((obs = it.GetNext()) != nullptr)
       if (obs->IsActive())
         return true;
   }
   return false;
 }
 
 }  // namespace cc