Return overlay resources to renderers in larger batches.

cc/resources/resource_provider.cc

Index: cc/resources/resource_provider.cc
diff --git a/cc/resources/resource_provider.cc b/cc/resources/resource_provider.cc
index e7d309db8a964fa061bd76ef29ba3d21fcd78886..d724bfd8567f0394f8fc6aff8a7b9a6a1a280236 100644
--- a/cc/resources/resource_provider.cc
+++ b/cc/resources/resource_provider.cc
@@ -1033,10 +1033,14 @@ void ResourceProvider::UnlockForRead(ResourceId id) {
       // The resource belongs to this ResourceProvider, so it can be destroyed.
       DeleteResourceInternal(it, NORMAL);
     } else {
-      ChildMap::iterator child_it = children_.find(resource->child_id);
-      ResourceIdArray unused;
-      unused.push_back(id);
-      DeleteAndReturnUnusedResourcesToChild(child_it, NORMAL, unused);
+      if (batch_return_resources_) {
+        batched_returning_resources_[resource->child_id].push_back(id);
+      } else {
+        ChildMap::iterator child_it = children_.find(resource->child_id);
+        ResourceIdArray unused;
+        unused.push_back(id);
+        DeleteAndReturnUnusedResourcesToChild(child_it, NORMAL, unused);
+      }
     }
   }
 }
@@ -1663,6 +1667,18 @@ void ResourceProvider::ReceiveReturnsFromParent(
   }
 }
 
+void ResourceProvider::SetBatchReturnResources(bool batch) {
+  batch_return_resources_ = batch;
+  if (!batch) {
+    for (const auto& resources : batched_returning_resources_) {
+      ChildMap::iterator child_it = children_.find(resources.first);
+      DCHECK(child_it != children_.end());

[Daniele Castagna, 2017/03/24 01:44:43]

nit: DCHECK_NE?

+      DeleteAndReturnUnusedResourcesToChild(child_it, NORMAL, resources.second);
+    }
+    batched_returning_resources_.clear();
+  }
+}
+
 #if defined(OS_ANDROID)
 void ResourceProvider::SendPromotionHints(
     const OverlayCandidateList::PromotionHintInfoMap& promotion_hints) {