Adding four bezel gestures

ash/volume_control_delegate.h

Index: ash/volume_control_delegate.h
diff --git a/ash/volume_control_delegate.h b/ash/volume_control_delegate.h
index 46b3cf3a8f6be5e780c24e889d00889bde1493ac..d922ea689262c584b7699576ad673bbc9703f1f0 100644
--- a/ash/volume_control_delegate.h
+++ b/ash/volume_control_delegate.h
@@ -20,6 +20,10 @@ class VolumeControlDelegate {
   virtual bool HandleVolumeMute(const ui::Accelerator& accelerator) = 0;
   virtual bool HandleVolumeDown(const ui::Accelerator& accelerator) = 0;
   virtual bool HandleVolumeUp(const ui::Accelerator& accelerator) = 0;
+
+  // Requests that the volume be set to |percent|, in the range
+  // [0.0, 100.0].
+  virtual void SetVolumePercent(double percent) = 0;
 };
 
 }  // namespace ash