Re-land^2 WebVR compositor bypass via BrowserMain context + mailbox

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 c699905019dff22bee1b1b63e2c6d2f13e57e77e..27729ceb676240fc988013b5758f6ef5e95006d4 100644
--- a/device/vr/test/fake_vr_device.cc
+++ b/device/vr/test/fake_vr_device.cc
@@ -72,7 +72,11 @@ void FakeVRDevice::ExitPresent() {
   OnExitPresent();
 }
 
-void FakeVRDevice::SubmitFrame(mojom::VRPosePtr pose) {}
+void FakeVRDevice::SubmitFrame(mojom::VRPosePtr pose,
+                               mojom::VRSubmitFrameClientPtr submit_client) {
+  submit_client->OnSubmitFrameTransferred();
+  submit_client->OnSubmitFrameRendered();
+}
 
 void FakeVRDevice::UpdateLayerBounds(int16_t frame_index,
                                      mojom::VRLayerBoundsPtr leftBounds,