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

device/vr/vr_service.mojom

Index: device/vr/vr_service.mojom
diff --git a/device/vr/vr_service.mojom b/device/vr/vr_service.mojom
index 2af38f579633e856444ee7611122b8e7cb1118eb..8849743df3caaca6bda9a7f1875631345d64b805 100644
--- a/device/vr/vr_service.mojom
+++ b/device/vr/vr_service.mojom
@@ -5,6 +5,8 @@
 module device.mojom;
 
 import "mojo/common/time.mojom";
+import "gpu/ipc/common/mailbox.mojom";
+import "gpu/ipc/common/sync_token.mojom";
 
 // A field of view, given by 4 degrees describing the view from a center point.
 struct VRFieldOfView {
@@ -85,14 +87,22 @@ interface VRServiceClient {
                      VRDisplayInfo displayInfo);
 };
 
+interface VRSubmitFrameClient {
+  OnSubmitFrameTransferred();
+  OnSubmitFrameRendered();
+};
+
 interface VRDisplay {
   ResetPose();
 
   RequestPresent(bool secureOrigin) => (bool success);
   ExitPresent();
-  SubmitFrame(VRPose? pose);
+  SubmitFrame(int16 frameId, gpu.mojom.Mailbox mailbox,
+              gpu.mojom.SyncToken syncToken,
+              VRSubmitFrameClient client);
   UpdateLayerBounds(int16 frameId, VRLayerBounds leftBounds,
-                    VRLayerBounds rightBounds);
+                    VRLayerBounds rightBounds, int16 sourceWidth,
+                    int16 sourceHeight);
   GetVRVSyncProvider(VRVSyncProvider& request);
 };