cc: Add some more infrastructure for two trees

cc/layer_tree_impl.cc

 // 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.
 
 #include "cc/layer_tree_impl.h"
 
 #include "cc/layer_tree_host_common.h"
 #include "cc/layer_tree_host_impl.h"
 
 namespace cc {
@@ skipping 88 matching lines @@
 }
 
 TileManager* LayerTreeImpl::tile_manager() const {
   return layer_tree_host_impl_->tileManager();
 }
 
 FrameRateCounter* LayerTreeImpl::frame_rate_counter() const {
   return layer_tree_host_impl_->fpsCounter();
 }
 
+bool LayerTreeImpl::IsActiveTree() const {
+  return layer_tree_host_impl_->activeTree() == this;
+}
+
+bool LayerTreeImpl::IsPendingTree() const {
+  return layer_tree_host_impl_->pendingTree() == this;
+}
+
+LayerImpl* LayerTreeImpl::ActiveTreeLayerById(int id) {
+  LayerTreeImpl* tree = layer_tree_host_impl_->activeTree();
+  if (!tree)
+    return NULL;
+  return tree->LayerById(id);
+}
+
+LayerImpl* LayerTreeImpl::PendingTreeLayerById(int id) {
+  LayerTreeImpl* tree = layer_tree_host_impl_->pendingTree();
+  if (!tree)
+    return NULL;
+  return tree->LayerById(id);
+}
+
 void LayerTreeImpl::SetNeedsRedraw() {
   layer_tree_host_impl_->setNeedsRedraw();
 }
 
 void LayerTreeImpl::SetNeedsUpdateDrawProperties() {
   layer_tree_host_impl_->setNeedsUpdateDrawProperties();
 }
 
 const LayerTreeDebugState& LayerTreeImpl::debug_state() const {
   return layer_tree_host_impl_->debugState();
@@ skipping 14 matching lines @@
 std::string LayerTreeImpl::layer_tree_as_text() const {
   return layer_tree_host_impl_->layerTreeAsText();
 }
 
 DebugRectHistory* LayerTreeImpl::debug_rect_history() const {
   return layer_tree_host_impl_->debugRectHistory();
 }
 
 
 } // namespace cc