Isolate a presenting VR device from pages other than the one presenting.

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 6c5b0500f7b430b7f1ce1f0e6b32bd5c506dc062..f1434edaeeede20269225b1df182eedb986acb8e 100644
--- a/device/vr/vr_device.h
+++ b/device/vr/vr_device.h
@@ -35,10 +35,9 @@ class VRDevice {
   virtual VRPosePtr GetPose() = 0;
   virtual void ResetPose() = 0;
 
-  virtual void RequestPresent(){};
+  virtual bool RequestPresent() { return true; };
   virtual void ExitPresent(){};
-
-  virtual void SubmitFrame(){};
+  virtual void SubmitFrame(VRPosePtr pose){};
   virtual void UpdateLayerBounds(VRLayerBoundsPtr leftBounds,
                                  VRLayerBoundsPtr rightBounds){};