[cc] Evict UIResources when the renderer is not visible

cc/trees/layer_tree_host_impl.h

 // 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.
 
 #ifndef CC_TREES_LAYER_TREE_HOST_IMPL_H_
 #define CC_TREES_LAYER_TREE_HOST_IMPL_H_
 
 #include <list>
 #include <string>
 #include <vector>
@@ skipping 324 matching lines @@
   TopControlsManager* top_controls_manager() {
     return top_controls_manager_.get();
   }
 
   Proxy* proxy() const { return proxy_; }
 
   AnimationRegistrar* animation_registrar() const {
     return animation_registrar_.get();
   }
 
+  uint64 ui_resource_eviction_count() const {
+    return ui_resource_eviction_count_;
+  }
+
   void SetDebugState(const LayerTreeDebugState& new_debug_state);
   const LayerTreeDebugState& debug_state() const { return debug_state_; }
 
   class CC_EXPORT CullRenderPassesWithCachedTextures {
  public:
     bool ShouldRemoveRenderPass(const RenderPassDrawQuad& quad,
                                 const FrameData& frame) const;
 
     // Iterates from the root first, in order to remove the surfaces closest
     // to the root with cached textures, and all surfaces that draw into
@@ skipping 237 matching lines @@
 
   base::TimeTicks current_frame_timeticks_;
   base::Time current_frame_time_;
 
   scoped_ptr<AnimationRegistrar> animation_registrar_;
 
   RenderingStatsInstrumentation* rendering_stats_instrumentation_;
 
   bool need_to_update_visible_tiles_before_draw_;
 
+  // The number of times that UI resources have been evicted since creation.
+  // This is passed to LayerTreeHost at frame creation. If the LayerTreeHost
+  // has not recreated its resources for this eviction count, it will recreate
+  // all resources and pass this counter back through the UI resource update
+  // queue.
+  uint64 ui_resource_eviction_count_;
+
   // Optional callback to notify of new tree activations.
   base::Closure tree_activation_callback_;
 
   DISALLOW_COPY_AND_ASSIGN(LayerTreeHostImpl);
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_LAYER_TREE_HOST_IMPL_H_