Allow VRDisplay to specify which frame the layer bounds should be updated at.

device/vr/test/fake_vr_device.cc

Index: device/vr/test/fake_vr_device.cc
diff --git a/device/vr/test/fake_vr_device.cc b/device/vr/test/fake_vr_device.cc
index cd478b2771afcb3e3b9aff601e26fb0a3d33ba65..d0853debfc5959f59cd3a31a528a9884790530df 100644
--- a/device/vr/test/fake_vr_device.cc
+++ b/device/vr/test/fake_vr_device.cc
@@ -73,7 +73,8 @@ void FakeVRDevice::ExitPresent() {
 
 void FakeVRDevice::SubmitFrame(mojom::VRPosePtr pose) {}
 
-void FakeVRDevice::UpdateLayerBounds(mojom::VRLayerBoundsPtr leftBounds,
+void FakeVRDevice::UpdateLayerBounds(int16_t frame_index,
+                                     mojom::VRLayerBoundsPtr leftBounds,
                                      mojom::VRLayerBoundsPtr rightBounds) {}
 
 void FakeVRDevice::GetVRVSyncProvider(mojom::VRVSyncProviderRequest request) {}