Setup LayerTree class, refactor 2 functions from LayerTreeHost to it.

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 22 matching lines @@
 #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.h"
 #include "cc/trees/layer_tree_host_client.h"
 #include "cc/trees/layer_tree_settings.h"
 #include "cc/trees/mutator_host_client.h"
 #include "cc/trees/proxy.h"
 #include "cc/trees/swap_promise_monitor.h"
 #include "third_party/skia/include/core/SkColor.h"
 #include "ui/gfx/geometry/rect.h"
 
 namespace gpu {
 class GpuMemoryBufferManager;
@@ skipping 366 matching lines @@
   }
 
   EnginePictureCache* engine_picture_cache() const {
     return engine_picture_cache_ ? engine_picture_cache_.get() : nullptr;
   }
 
   ClientPictureCache* client_picture_cache() const {
     return client_picture_cache_ ? client_picture_cache_.get() : nullptr;
   }
 
+  LayerTree* layer_tree() { return &layer_tree_; }

[Khushal, 2016/07/18 16:59:33]

Can you change this to LayerTree* GetLayerTree() const; and define in the
header? When the method is added to the LayerTreeHost interface it won't be an
accessor.

[xingliu, 2016/07/19 22:47:38]

Done.

+
  protected:
   LayerTreeHost(InitParams* params, CompositorMode mode);
   void InitializeThreaded(
       scoped_refptr<base::SingleThreadTaskRunner> main_task_runner,
       scoped_refptr<base::SingleThreadTaskRunner> impl_task_runner,
       std::unique_ptr<BeginFrameSource> external_begin_frame_source);
   void InitializeSingleThreaded(
       LayerTreeHostSingleThreadClient* single_thread_client,
       scoped_refptr<base::SingleThreadTaskRunner> main_task_runner,
       std::unique_ptr<BeginFrameSource> external_begin_frame_source);
@@ skipping 153 matching lines @@
   std::set<SwapPromiseMonitor*> swap_promise_monitor_;
 
   PropertyTrees property_trees_;
 
   using LayerIdMap = std::unordered_map<int, Layer*>;
   LayerIdMap layer_id_map_;
 
   using ElementLayersMap = std::unordered_map<ElementId, Layer*, ElementIdHash>;
   ElementLayersMap element_layers_map_;
 
-  // Set of layers that need to push properties.
-  std::unordered_set<Layer*> layers_that_should_push_properties_;
-
   uint32_t surface_client_id_;
   uint32_t next_surface_sequence_;
   uint32_t num_consecutive_frames_suitable_for_gpu_ = 0;
 
+  // Layer tree that hold layers.
+  LayerTree layer_tree_;
+
   DISALLOW_COPY_AND_ASSIGN(LayerTreeHost);
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_LAYER_TREE_HOST_H_