CC Animation: Use ElementId to attach CC animation players.

ui/compositor/layer.h

 // Copyright (c) 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 UI_COMPOSITOR_LAYER_H_
 #define UI_COMPOSITOR_LAYER_H_
 
 #include <stddef.h>
 
 #include <memory>
 #include <string>
 #include <vector>
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/message_loop/message_loop.h"
 #include "cc/base/region.h"
 #include "cc/layers/content_layer_client.h"
 #include "cc/layers/layer_client.h"
 #include "cc/layers/surface_layer.h"
 #include "cc/layers/texture_layer_client.h"
 #include "cc/resources/texture_mailbox.h"
 #include "cc/surfaces/surface_id.h"
+#include "cc/trees/element_id.h"
 #include "third_party/skia/include/core/SkColor.h"
 #include "third_party/skia/include/core/SkRegion.h"
 #include "ui/compositor/compositor.h"
 #include "ui/compositor/layer_animation_delegate.h"
 #include "ui/compositor/layer_delegate.h"
 #include "ui/compositor/layer_type.h"
 #include "ui/gfx/geometry/rect.h"
 #include "ui/gfx/image/image_skia.h"
 #include "ui/gfx/transform.h"
 
@@ skipping 46 matching lines @@
         const_cast<const Layer*>(this)->GetCompositor());
   }
   const Compositor* GetCompositor() const;
 
   // Called by the compositor when the Layer is set as its root Layer. This can
   // only ever be called on the root layer.
   void SetCompositor(Compositor* compositor,
                      scoped_refptr<cc::Layer> root_layer);
   void ResetCompositor();
 
+  static cc::ElementId NextElementId();
+
   LayerDelegate* delegate() { return delegate_; }
   void set_delegate(LayerDelegate* delegate) { delegate_ = delegate; }
 
   LayerOwner* owner() { return owner_; }
 
   // Adds a new Layer to this Layer.
   void Add(Layer* child);
 
   // Removes a Layer from this Layer.
   void Remove(Layer* child);
@@ skipping 401 matching lines @@
   // The size of the frame or texture in DIP, set when SetShowDelegatedContent
   // or SetTextureMailbox was called.
   gfx::Size frame_size_in_dip_;
 
   DISALLOW_COPY_AND_ASSIGN(Layer);
 };
 
 }  // namespace ui
 
 #endif  // UI_COMPOSITOR_LAYER_H_