cc: Add a main thread LayerListIterator

cc/trees/layer_tree_host.h

 // 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.
 
 #ifndef CC_TREES_LAYER_TREE_HOST_H_
 #define CC_TREES_LAYER_TREE_HOST_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 13 matching lines @@
 #include "cc/base/cc_export.h"
 #include "cc/debug/frame_timing_tracker.h"
 #include "cc/debug/micro_benchmark.h"
 #include "cc/debug/micro_benchmark_controller.h"
 #include "cc/input/event_listener_properties.h"
 #include "cc/input/input_handler.h"
 #include "cc/input/layer_selection_bound.h"
 #include "cc/input/scrollbar.h"
 #include "cc/input/top_controls_state.h"
 #include "cc/layers/layer_collections.h"
+#include "cc/layers/layer_list_iterator.h"
 #include "cc/output/output_surface.h"
 #include "cc/output/renderer_capabilities.h"
 #include "cc/output/swap_promise.h"
 #include "cc/resources/resource_format.h"
 #include "cc/resources/scoped_ui_resource.h"
 #include "cc/surfaces/surface_sequence.h"
 #include "cc/trees/compositor_mode.h"
 #include "cc/trees/layer_tree_host_client.h"
 #include "cc/trees/layer_tree_settings.h"
 #include "cc/trees/mutator_host_client.h"
@@ skipping 96 matching lines @@
   void DidInitializeOutputSurface();
   void DidFailToInitializeOutputSurface();
   virtual std::unique_ptr<LayerTreeHostImpl> CreateLayerTreeHostImpl(
       LayerTreeHostImplClient* client);
   void DidLoseOutputSurface();
   bool output_surface_lost() const { return output_surface_lost_; }
   void DidCommitAndDrawFrame() { client_->DidCommitAndDrawFrame(); }
   void DidCompleteSwapBuffers() { client_->DidCompleteSwapBuffers(); }
   bool UpdateLayers();
 
+  LayerListIterator<Layer> begin();
+  LayerListIterator<Layer> end();
+  LayerListReverseIterator<Layer> rbegin();
+  LayerListReverseIterator<Layer> rend();
+
   // Called when the compositor completed page scale animation.
   void DidCompletePageScaleAnimation();
 
   LayerTreeHostClient* client() { return client_; }
   const base::WeakPtr<InputHandler>& GetInputHandler() {
     return input_handler_weak_ptr_;
   }
 
   void NotifyInputThrottledUntilCommit();
 
@@ skipping 433 matching lines @@
 
   uint32_t surface_id_namespace_;
   uint32_t next_surface_sequence_;
 
   DISALLOW_COPY_AND_ASSIGN(LayerTreeHost);
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_LAYER_TREE_HOST_H_