[cc] Evict UIResources when the renderer is not visible

cc/trees/layer_tree_impl.h

Index: cc/trees/layer_tree_impl.h
diff --git a/cc/trees/layer_tree_impl.h b/cc/trees/layer_tree_impl.h
index 3b186932663ae4f585d5cb46cf41603e094605c5..835d7f7c81148b9c1f70bdf7da4eef8dc5f5df43 100644
--- a/cc/trees/layer_tree_impl.h
+++ b/cc/trees/layer_tree_impl.h
@@ -180,6 +180,12 @@ class CC_EXPORT LayerTreeImpl {
 
   void DidBecomeActive();
 
+  void SetUIResourceEvictionCountRecreated(
+      uint64 ui_resource_eviction_count_recreated);
+  uint64 ui_resource_eviction_count_recreated() const {
+    return ui_resource_eviction_count_recreated_;
+  }
+
   bool ContentsTexturesPurged() const;
   void SetContentsTexturesPurged();
   void ResetContentsTexturesPurged();
@@ -244,6 +250,12 @@ class CC_EXPORT LayerTreeImpl {
   // rendering and input event hit testing.
   LayerImplList render_surface_layer_list_;
 
+  // The UI resource eviction count most recently acked. This value is updated
+  // through ProcessUIResourceRequestQueue. If this value is not equal to
+  // |layer_tree_host_impl_|'s UI resource eviction count, then this tree may
+  // may reference evicted UI resources and cannot be drawn.
+  uint64 ui_resource_eviction_count_recreated_;
+
   bool contents_textures_purged_;
   bool viewport_size_invalid_;
   bool needs_update_draw_properties_;