Reland of cc: Remove frame queuing from the scheduler.

cc/trees/single_thread_proxy.cc

Index: cc/trees/single_thread_proxy.cc
diff --git a/cc/trees/single_thread_proxy.cc b/cc/trees/single_thread_proxy.cc
index 502599f36a97380553a0a64fd35dd7d4ebf7deae..4b245a9e4bc76a9861cdbdb8c16e69058d943763 100644
--- a/cc/trees/single_thread_proxy.cc
+++ b/cc/trees/single_thread_proxy.cc
@@ -299,13 +299,10 @@ void SingleThreadProxy::Stop() {
     // Take away the CompositorFrameSink before destroying things so it doesn't
     // try to call into its client mid-shutdown.
     layer_tree_host_impl_->ReleaseCompositorFrameSink();
-
-    BlockingTaskRunner::CapturePostTasks blocked(
-        task_runner_provider_->blocking_main_thread_task_runner());
     scheduler_on_impl_thread_ = nullptr;
     layer_tree_host_impl_ = nullptr;
   }
-  layer_tree_host_ = NULL;
+  layer_tree_host_ = nullptr;
 }
 
 void SingleThreadProxy::SetMutator(std::unique_ptr<LayerTreeMutator> mutator) {