cc: Add id->LayerImpl map to LayerTreeImpl

cc/layer_tree_impl.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_LAYER_TREE_IMPL_H_
 #define CC_LAYER_TREE_IMPL_H_
 
+#include "base/hash_tables.h"
 #include "cc/layer_impl.h"
 
+#if defined(COMPILER_GCC)

[danakj, 2012/12/13 23:57:11]

I would expect you to need an MSVC version too. If you do, see cc/hash_pair.h

[enne (OOO), 2012/12/14 00:21:12]

Nope.  That's just for std::pair being weird.  See layer_sorter.h or
layer_tree_host.h

+namespace BASE_HASH_NAMESPACE {
+template<>
+struct hash<cc::LayerImpl*> {
+  size_t operator()(cc::LayerImpl* ptr) const {
+    return hash<size_t>()(reinterpret_cast<size_t>(ptr));
+  }
+};
+} // namespace BASE_HASH_NAMESPACE
+#endif // COMPILER
+
 namespace cc {
 
 class DebugRectHistory;
 class FrameRateCounter;
 class HeadsUpDisplayLayerImpl;
 class LayerTreeDebugState;
 class LayerTreeHostImpl;
 class LayerTreeImpl;
 class LayerTreeSettings;
 class OutputSurface;
@@ skipping 43 matching lines @@
   void set_hud_layer(HeadsUpDisplayLayerImpl* layer_impl) { hud_layer_ = layer_impl; }
 
   LayerImpl* root_scroll_layer() { return root_scroll_layer_; }
   void set_root_scroll_layer(LayerImpl* layer_impl) { root_scroll_layer_ = layer_impl; }
 
   LayerImpl* currently_scrolling_layer() { return currently_scrolling_layer_; }
   void set_currently_scrolling_layer(LayerImpl* layer_impl) { currently_scrolling_layer_ = layer_impl; }
 
   void ClearCurrentlyScrollingLayer();
 
+  LayerImpl* LayerById(int id);
+
+  // These should be called by LayerImpl's ctor/dtor.
+  void RegisterLayer(LayerImpl* layer);
+  void UnregisterLayer(LayerImpl* layer);
+
 protected:
   LayerTreeImpl(LayerTreeHostImpl* layer_tree_host_impl);
 
   LayerTreeHostImpl* layer_tree_host_impl_;
   int source_frame_number_;
   scoped_ptr<LayerImpl> root_layer_;
   HeadsUpDisplayLayerImpl* hud_layer_;
   LayerImpl* root_scroll_layer_;
   LayerImpl* currently_scrolling_layer_;
 
+  typedef base::hash_map<int, LayerImpl*> LayerIdMap;
+  LayerIdMap layer_id_map_;
+
   // Persisted state
   int scrolling_layer_id_from_previous_tree_;
 
   DISALLOW_COPY_AND_ASSIGN(LayerTreeImpl);
 };
 
 }
 
 #endif  // CC_LAYER_TREE_IMPL_H_