Use layout test support flag to turn on single thread compositor proxy scheduler

content/renderer/render_thread_impl.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/renderer/render_thread_impl.h"
 
 #include <algorithm>
 #include <limits>
 #include <map>
 #include <vector>
@@ skipping 1397 matching lines @@
 
 bool RenderThreadImpl::IsOneCopyEnabled() {
   return is_one_copy_enabled_;
 }
 
 bool RenderThreadImpl::IsElasticOverscrollEnabled() {
   return is_elastic_overscroll_enabled_;
 }
 
 bool RenderThreadImpl::UseSingleThreadScheduler() {
-  base::CommandLine* cmd = base::CommandLine::ForCurrentProcess();
-  return !cmd->HasSwitch(switches::kDisableSingleThreadProxyScheduler);
+  // TODO(enne): using the scheduler introduces additional composite steps
+  // that create flakiness.  This should go away eventually.
+  return !layout_test_mode_;
 }
 
 uint32 RenderThreadImpl::GetImageTextureTarget() {
   return use_image_texture_target_;
 }
 
 scoped_refptr<base::SingleThreadTaskRunner>
 RenderThreadImpl::GetCompositorMainThreadTaskRunner() {
   return main_thread_compositor_task_runner_;
 }
@@ skipping 453 matching lines @@
 }
 
 void RenderThreadImpl::PendingRenderFrameConnect::OnConnectionError() {
   size_t erased =
       RenderThreadImpl::current()->pending_render_frame_connects_.erase(
           routing_id_);
   DCHECK_EQ(1u, erased);
 }
 
 }  // namespace content