Enable BeginFrame scheduling on aura

content/renderer/gpu/render_widget_compositor.cc

 // Copyright (c) 2013 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/gpu/render_widget_compositor.h"
 
 #include <limits>
 #include <string>
 
 #include "base/command_line.h"
@@ skipping 183 matching lines @@
   base::CommandLine* cmd = base::CommandLine::ForCurrentProcess();
 
   cc::LayerTreeSettings settings;
 
   // For web contents, layer transforms should scale up the contents of layers
   // to keep content always crisp when possible.
   settings.layer_transforms_should_scale_layer_contents = true;
 
   settings.throttle_frame_production =
       !cmd->HasSwitch(switches::kDisableGpuVsync);
-  settings.use_external_begin_frame_source =
-      cmd->HasSwitch(switches::kEnableBeginFrameScheduling);

[danakj, 2015/03/25 17:40:38]

no longer used then? shall we remove the switch?

[simonhong, 2015/03/25 18:05:22]

Yep. removed.

+#if !defined(OS_MACOSX)
+  settings.use_external_begin_frame_source = true;
+#endif
   settings.main_frame_before_activation_enabled =
       cmd->HasSwitch(cc::switches::kEnableMainFrameBeforeActivation) &&
       !cmd->HasSwitch(cc::switches::kDisableMainFrameBeforeActivation);
   settings.report_overscroll_only_for_scrollable_axes =
       !compositor_deps_->IsElasticOverscrollEnabled();
   settings.accelerated_animation_enabled =
       !cmd->HasSwitch(cc::switches::kDisableThreadedAnimation);
   settings.use_display_lists = cmd->HasSwitch(switches::kEnableSlimmingPaint);
 
   settings.default_tile_size = CalculateDefaultTileSize();
@@ skipping 690 matching lines @@
   cc::ContextProvider* provider =
       compositor_deps_->GetSharedMainThreadContextProvider();
   // provider can be NULL after the GPU process crashed enough times and we
   // don't want to restart it any more (falling back to software).
   if (!provider)
     return;
   provider->ContextGL()->RateLimitOffscreenContextCHROMIUM();
 }
 
 }  // namespace content