Delay activation/draw on GPU tile work completion

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 6547109d3a5f35a9a409073f1a0bc3d6b93041c2..0a69369094f6d94905bbeb175cb70ae86844d4eb 100644
--- a/cc/resources/resource_provider.cc
+++ b/cc/resources/resource_provider.cc
@@ -972,6 +972,23 @@ void ResourceProvider::GenerateSyncTokenForResources(
   }
 }
 
+gpu::SyncToken ResourceProvider::GetSyncTokenForResource(
+    ResourceId resource_id) {
+  Resource* resource = GetResource(resource_id);
+  return resource->mailbox().sync_token();
+}
+
+gpu::SyncToken ResourceProvider::GetSyncTokenForResources(
+    const ResourceIdArray& resource_ids) {
+  gpu::SyncToken latest_sync_token;
+  for (ResourceId id : resource_ids) {
+    const gpu::SyncToken& sync_token = GetResource(id)->mailbox().sync_token();
+    if (sync_token.release_count() > latest_sync_token.release_count())
+      latest_sync_token = sync_token;
+  }
+  return latest_sync_token;
+}
+
 ResourceProvider::Resource* ResourceProvider::InsertResource(
     ResourceId id,
     Resource resource) {