cc: Add some more infrastructure for two trees

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"
 
@@ skipping 22 matching lines @@
 class TileManager;
 
 class CC_EXPORT LayerTreeImpl {
  public:
   static scoped_ptr<LayerTreeImpl> create(LayerTreeHostImpl* layer_tree_host_impl)
   {
     return make_scoped_ptr(new LayerTreeImpl(layer_tree_host_impl));
   }
   virtual ~LayerTreeImpl();
 
-  // Methods called by the layer tree that pass-through to LHTI.
+  // Methods called by the layer tree that pass-through or access LTHI.
   // ---------------------------------------------------------------------------
   const LayerTreeSettings& settings() const;
   OutputSurface* output_surface() const;
   ResourceProvider* resource_provider() const;
   TileManager* tile_manager() const;
   FrameRateCounter* frame_rate_counter() const;
+  bool IsActiveTree() const;
+  bool IsPendingTree() const;
+  LayerImpl* ActiveTreeLayerById(int id);

[nduca, 2012/12/14 02:18:43]

Get or FindActiveTreeLayerByBlah

[enne (OOO), 2012/12/14 17:30:53]

Ok, sure.  FindActiveTreeLayerByBlah, it is.

+  LayerImpl* PendingTreeLayerById(int id);
 
   // Tree specific methods exposed to layer-impl tree.
   // ---------------------------------------------------------------------------
   void SetNeedsRedraw();
   void SetNeedsUpdateDrawProperties();
 
   // TODO(nduca): These are implemented in cc files temporarily, but will become
   // trivial accessors in a followup patch.
   const LayerTreeDebugState& debug_state() const;
   float device_scale_factor() const;
@@ skipping 43 matching lines @@
 
   // Persisted state
   int scrolling_layer_id_from_previous_tree_;
 
   DISALLOW_COPY_AND_ASSIGN(LayerTreeImpl);
 };
 
 }
 
 #endif  // CC_LAYER_TREE_IMPL_H_