cc: Block commit on activate by setting a flag on LayerTreeHost.

cc/trees/thread_proxy.cc

Index: cc/trees/thread_proxy.cc
diff --git a/cc/trees/thread_proxy.cc b/cc/trees/thread_proxy.cc
index 7f9baa8b86deee88b4f07231faabf9954ec7ea97..cb3373e9ebb26c10677549d9965cee18ca3cd677 100644
--- a/cc/trees/thread_proxy.cc
+++ b/cc/trees/thread_proxy.cc
@@ -76,6 +76,8 @@ ThreadProxy::ThreadProxy(
       textures_acquired_(true),
       in_composite_and_readback_(false),
       manage_tiles_pending_(false),
+      commit_waits_for_activation_(false),
+      inside_commit_(false),
       weak_factory_on_impl_thread_(this),
       weak_factory_(this),
       begin_frame_sent_to_main_thread_completion_event_on_impl_thread_(NULL),
@@ -502,6 +504,12 @@ void ThreadProxy::SetNeedsRedraw(gfx::Rect damage_rect) {
                  damage_rect));
 }
 
+void ThreadProxy::SetNextCommitWaitsForActivation() {
+  DCHECK(IsMainThread());
+  DCHECK(!inside_commit_);
+  commit_waits_for_activation_ = true;
+}
+
 void ThreadProxy::SetDeferCommits(bool defer_commits) {
   DCHECK(IsMainThread());
   DCHECK_NE(defer_commits_, defer_commits);
@@ -929,10 +937,12 @@ void ThreadProxy::ScheduledActionCommit() {
   current_resource_update_controller_on_impl_thread_->Finalize();
   current_resource_update_controller_on_impl_thread_.reset();
 
+  inside_commit_ = true;
   layer_tree_host_impl_->BeginCommit();
   layer_tree_host_->BeginCommitOnImplThread(layer_tree_host_impl_.get());
   layer_tree_host_->FinishCommitOnImplThread(layer_tree_host_impl_.get());
   layer_tree_host_impl_->CommitComplete();
+  inside_commit_ = false;
 
   SetInputThrottledUntilCommitOnImplThread(false);
 
@@ -942,8 +952,7 @@ void ThreadProxy::ScheduledActionCommit() {
   next_frame_is_newly_committed_frame_on_impl_thread_ = true;
 
   if (layer_tree_host_->settings().impl_side_painting &&
-      layer_tree_host_->BlocksPendingCommit() &&
-      layer_tree_host_impl_->pending_tree()) {
+      commit_waits_for_activation_) {
     // For some layer types in impl-side painting, the commit is held until
     // the pending tree is activated.  It's also possible that the
     // pending tree has already activated if there was no work to be done.
@@ -956,6 +965,8 @@ void ThreadProxy::ScheduledActionCommit() {
     commit_completion_event_on_impl_thread_ = NULL;
   }
 
+  commit_waits_for_activation_ = false;
+
   commit_complete_time_ = base::TimeTicks::HighResNow();
   begin_frame_to_commit_duration_history_.InsertSample(
       commit_complete_time_ - begin_frame_sent_to_main_thread_time_);