cc: Implement unified BeginFrame on aura

cc/base/switches.cc

Index: cc/base/switches.cc
diff --git a/cc/base/switches.cc b/cc/base/switches.cc
index d34821e0fac6bf348af5fd66c7d282d33b484a1e..60bcddf3af39f33aa999fe380dbae8b661f42c0d 100644
--- a/cc/base/switches.cc
+++ b/cc/base/switches.cc
@@ -64,6 +64,9 @@ const char kUIDisablePartialSwap[] = "ui-disable-partial-swap";
 // Enables the GPU benchmarking extension
 const char kEnableGpuBenchmarking[] = "enable-gpu-benchmarking";
 
+// Use a BeginFrame signal from browser to renderer to schedule rendering.
+const char kEnableBeginFrameScheduling[] = "enable-begin-frame-scheduling";
+
 // Renders a border around compositor layers to help debug and study
 // layer compositing.
 const char kShowCompositedLayerBorders[] = "show-composited-layer-borders";