(not for review yet)

cc/trees/layer_tree_host.h

Index: cc/trees/layer_tree_host.h
diff --git a/cc/trees/layer_tree_host.h b/cc/trees/layer_tree_host.h
index b5577e9697b31de8feae8f0bd243561aa70d0a15..3e473c20de7ed402e18c24e21410a4109cd8d2cc 100644
--- a/cc/trees/layer_tree_host.h
+++ b/cc/trees/layer_tree_host.h
@@ -88,6 +88,7 @@ struct CC_EXPORT UIResourceRequest {
   enum UIResourceRequestType {
     UIResourceCreate,
     UIResourceDelete,
+    UIResourceEvictionAck,
     UIResourceInvalidRequest
   };
 
@@ -96,6 +97,7 @@ struct CC_EXPORT UIResourceRequest {
   UIResourceRequestType type;
   UIResourceId id;
   scoped_refptr<UIResourceBitmap> bitmap;
+  uint64 ack;
 };
 
 class CC_EXPORT LayerTreeHost : NON_EXPORTED_BASE(public RateLimiterClient) {
@@ -283,6 +285,12 @@ class CC_EXPORT LayerTreeHost : NON_EXPORTED_BASE(public RateLimiterClient) {
   // Deletes a UI resource.  May safely be called more than once.
   virtual void DeleteUIResource(UIResourceId id);
 
+  // Record the eviction count sent by the LayerTreeHostImpl at BeginFrame.
+  // If |ui_resource_eviction_count| value is more recent than the current
+  // value of |ui_resource_eviction_count_last_acked_|, then add the recreation
+  // of all UI resources to the UIResourceRequestQueue.
+  void SetUIResourceEvictionCountToAck(uint64 ui_resource_eviction_count);
+
   bool UsingSharedMemoryResources();
   int id() const { return tree_id_; }
 
@@ -327,6 +335,7 @@ class CC_EXPORT LayerTreeHost : NON_EXPORTED_BASE(public RateLimiterClient) {
 
   typedef std::list<UIResourceRequest> UIResourceRequestQueue;
   UIResourceRequestQueue ui_resource_request_queue_;
+  uint64 ui_resource_eviction_count_last_acked_;
 
   void CalculateLCDTextMetricsCallback(Layer* layer);