cc : Add OnOpacityAnimated to effect tree

cc/trees/layer_tree_host_impl.cc

 // Copyright 2011 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/trees/layer_tree_host_impl.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 3900 matching lines @@
 }
 
 void LayerTreeHostImpl::SetTreeLayerOpacityMutated(ElementId element_id,
                                                    LayerTreeImpl* tree,
                                                    float opacity) {
   if (!tree)
     return;
 
   LayerImpl* layer = tree->LayerByElementId(element_id);
   if (layer)
-    layer->OnOpacityAnimated(opacity);
+    tree->property_trees()->effect_tree.OnOpacityAnimated(
+        opacity, layer->effect_tree_index(), tree);

[ajuma, 2016/08/18 18:49:26]

Can we get the effect tree index from the id to index map to remove the
dependency on |layer| altogether? Is the problem that we don't have a way to map
from element_id to layer id? If so, I think the id-to-index map should really be
mapping ElementId to index rather than layer id to index. (But that change can
happen in a separate CL.)

[jaydasika, 2016/08/18 19:57:52]

Acknowledged. Will do that in a separate CL.

 }
 
 void LayerTreeHostImpl::SetTreeLayerTransformMutated(
     ElementId element_id,
     LayerTreeImpl* tree,
     const gfx::Transform& transform) {
   if (!tree)
     return;
 
   LayerImpl* layer = tree->LayerByElementId(element_id);
@@ skipping 169 matching lines @@
   return task_runner_provider_->HasImplThread();
 }
 
 bool LayerTreeHostImpl::CommitToActiveTree() const {
   // In single threaded mode we skip the pending tree and commit directly to the
   // active tree.
   return !task_runner_provider_->HasImplThread();
 }
 
 }  // namespace cc