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 53b69b6fb03b660f03503402f789066ee0cadf96..8c427a1443f9c76dfa1e745ec3b4f9e94fbccb5d 100644
--- a/device/vr/test/fake_vr_device.cc
+++ b/device/vr/test/fake_vr_device.cc
@@ -82,7 +82,8 @@ 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) {}