CC Animation: Use ElementId to attach CC animation players.

cc/test/fake_picture_layer.h

 // 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.
 
 #ifndef CC_TEST_FAKE_PICTURE_LAYER_H_
 #define CC_TEST_FAKE_PICTURE_LAYER_H_
 
 #include <stddef.h>
 
 #include <memory>
 
 #include "base/memory/ref_counted.h"
 #include "cc/layers/picture_layer.h"
 #include "cc/playback/recording_source.h"
 
 namespace cc {
 class FakePictureLayer : public PictureLayer {
  public:
   static scoped_refptr<FakePictureLayer> Create(ContentLayerClient* client) {
-    return make_scoped_refptr(new FakePictureLayer(client));
+    auto layer = make_scoped_refptr(new FakePictureLayer(client));
+    layer->SetElementId(NextElementId());
+    return layer;
   }
 
   static scoped_refptr<FakePictureLayer> CreateWithRecordingSource(
       ContentLayerClient* client,
       std::unique_ptr<RecordingSource> source) {
-    return make_scoped_refptr(new FakePictureLayer(client, std::move(source)));
+    auto layer =
+        make_scoped_refptr(new FakePictureLayer(client, std::move(source)));
+    layer->SetElementId(NextElementId());
+    return layer;
   }
 
   std::unique_ptr<LayerImpl> CreateLayerImpl(LayerTreeImpl* tree_impl) override;
 
   int update_count() const { return update_count_; }
   void reset_update_count() { update_count_ = 0; }
 
   size_t push_properties_count() const { return push_properties_count_; }
   void reset_push_properties_count() { push_properties_count_ = 0; }
 
@@ skipping 12 matching lines @@
   ~FakePictureLayer() override;
 
   int update_count_;
   size_t push_properties_count_;
   bool always_update_resources_;
 };
 
 }  // namespace cc
 
 #endif  // CC_TEST_FAKE_PICTURE_LAYER_H_