cc: Move gpu rasterization flag from LayerImpl to LayerTreeImpl.

cc/trees/layer_tree_impl.cc

Index: cc/trees/layer_tree_impl.cc
diff --git a/cc/trees/layer_tree_impl.cc b/cc/trees/layer_tree_impl.cc
index 962ce7de13c18d3ffa4c573380fe097e628203fa..97e9c1754c9a18eb8f9740101b72ad3849675808 100644
--- a/cc/trees/layer_tree_impl.cc
+++ b/cc/trees/layer_tree_impl.cc
@@ -92,6 +92,7 @@ LayerTreeImpl::LayerTreeImpl(LayerTreeHostImpl* layer_tree_host_impl)
       min_page_scale_factor_(0),
       max_page_scale_factor_(0),
       scrolling_layer_id_from_previous_tree_(0),
+      use_gpu_rasterization_(false),
       contents_textures_purged_(false),
       requires_high_res_to_draw_(false),
       viewport_size_invalid_(false),
@@ -110,6 +111,11 @@ LayerTreeImpl::~LayerTreeImpl() {
 
 void LayerTreeImpl::Shutdown() { root_layer_.reset(); }
 
+void LayerTreeImpl::ReleaseResources() {
+  if (root_layer_)
+    ReleaseResourcesRecursive(root_layer_.get());
+}
+
 void LayerTreeImpl::SetRootLayer(scoped_ptr<LayerImpl> layer) {
   if (inner_viewport_scroll_layer_)
     inner_viewport_scroll_layer_->SetScrollOffsetDelegate(NULL);
@@ -220,6 +226,8 @@ void LayerTreeImpl::PushPropertiesTo(LayerTreeImpl* target_tree) {
   target_tree->set_background_color(background_color());
   target_tree->set_has_transparent_background(has_transparent_background());
 
+  target_tree->use_gpu_rasterization_ = use_gpu_rasterization();
+
   if (ContentsTexturesPurged())
     target_tree->SetContentsTexturesPurged();
   else
@@ -437,6 +445,14 @@ void LayerTreeImpl::ClearViewportLayers() {
   outer_viewport_scroll_layer_ = NULL;
 }
 
+void LayerTreeImpl::SetUseGpuRasterization(bool use_gpu) {
+  if (use_gpu == use_gpu_rasterization_)
+    return;
+
+  use_gpu_rasterization_ = use_gpu;
+  ReleaseResources();
+}
+
 void LayerTreeImpl::UpdateDrawProperties() {
   needs_update_draw_properties_ = false;
   render_surface_layer_list_.clear();
@@ -995,4 +1011,15 @@ const std::vector<LayerImpl*>& LayerTreeImpl::LayersWithCopyOutputRequest()
   return layers_with_copy_output_request_;
 }
 
+void LayerTreeImpl::ReleaseResourcesRecursive(LayerImpl* current) {
+  DCHECK(current);
+  current->ReleaseResources();
+  if (current->mask_layer())
+    ReleaseResourcesRecursive(current->mask_layer());
+  if (current->replica_layer())
+    ReleaseResourcesRecursive(current->replica_layer());
+  for (size_t i = 0; i < current->children().size(); ++i)
+    ReleaseResourcesRecursive(current->children()[i]);
+}
+
 }  // namespace cc