Plumbing through more WebVR presentation code

device/vr/vr_device.h

Index: device/vr/vr_device.h
diff --git a/device/vr/vr_device.h b/device/vr/vr_device.h
index 632aec5a5c19498c7897339fe08af51e4c07e008..6c5b0500f7b430b7f1ce1f0e6b32bd5c506dc062 100644
--- a/device/vr/vr_device.h
+++ b/device/vr/vr_device.h
@@ -35,6 +35,13 @@ class VRDevice {
   virtual VRPosePtr GetPose() = 0;
   virtual void ResetPose() = 0;
 
+  virtual void RequestPresent(){};
+  virtual void ExitPresent(){};
+
+  virtual void SubmitFrame(){};
+  virtual void UpdateLayerBounds(VRLayerBoundsPtr leftBounds,
+                                 VRLayerBoundsPtr rightBounds){};
+
  private:
   VRDeviceProvider* provider_;
   unsigned int id_;