cc: Fix resource eviction with impl-side painting.

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 "base/debug/trace_event.h"
 #include "cc/layer_tree_host_common.h"
 #include "cc/layer_tree_host_impl.h"
 #include "ui/gfx/vector2d_conversions.h"
 
 namespace cc {
 
 LayerTreeImpl::LayerTreeImpl(LayerTreeHostImpl* layer_tree_host_impl)
     : layer_tree_host_impl_(layer_tree_host_impl)
     , source_frame_number_(-1)
     , hud_layer_(0)
     , root_scroll_layer_(0)
     , currently_scrolling_layer_(0)
     , background_color_(0)
     , has_transparent_background_(false)
-    , scrolling_layer_id_from_previous_tree_(0) {
+    , scrolling_layer_id_from_previous_tree_(0)
+    , contents_textures_purged_(false) {
 }
 
 LayerTreeImpl::~LayerTreeImpl() {
   // Need to explicitly clear the tree prior to destroying this so that
   // the LayerTreeImpl pointer is still valid in the LayerImpl dtor.
   root_layer_.reset();
 }
 
 static LayerImpl* findRootScrollLayer(LayerImpl* layer)
 {
@@ skipping 175 matching lines @@
   layer->didBecomeActive();
   for (size_t i = 0; i < layer->children().size(); ++i)
     DidBecomeActiveRecursive(layer->children()[i]);
 }
 
 void LayerTreeImpl::DidBecomeActive() {
   if (RootLayer())
     DidBecomeActiveRecursive(RootLayer());
 }
 
+bool LayerTreeImpl::ContentsTexturesPurged() const {
+  return contents_textures_purged_;
+}
+
+void LayerTreeImpl::SetContentsTexturesPurged() {
+  contents_textures_purged_ = true;
+  layer_tree_host_impl_->OnCanDrawStateChangedForTree(this);
+}
+
+void LayerTreeImpl::ResetContentsTexturesPurged() {
+  contents_textures_purged_ = false;
+  layer_tree_host_impl_->OnCanDrawStateChangedForTree(this);
+}
+
 const LayerTreeSettings& LayerTreeImpl::settings() const {
   return layer_tree_host_impl_->settings();
 }
 
 OutputSurface* LayerTreeImpl::output_surface() const {
   return layer_tree_host_impl_->outputSurface();
 }
 
 ResourceProvider* LayerTreeImpl::resource_provider() const {
   return layer_tree_host_impl_->resourceProvider();
@@ skipping 71 matching lines @@
 
 AnimationRegistrar* LayerTreeImpl::animationRegistrar() const {
   return layer_tree_host_impl_->animationRegistrar();
 }
 
 const PinchZoomViewport& LayerTreeImpl::pinch_zoom_viewport() const {
   return layer_tree_host_impl_->pinchZoomViewport();
 }
 
 } // namespace cc