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 a77d4a9bf2dbb9d3370c89ae68c2a2d8bcc5ad3c..2eee52f99666c336098390877082cc3289c083ac 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_holder.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 {
@@ -84,19 +86,25 @@ interface VRServiceClient {
                      VRDisplayInfo displayInfo);
 };
 
+interface VRSubmitFrameClient {
+  OnSubmitFrameTransferred();
+  OnSubmitFrameRendered();
+};
+
 interface VRDisplay {
   ResetPose();
 
-  RequestPresent(bool secureOrigin) => (bool success);
+  RequestPresent(bool secureOrigin, VRSubmitFrameClient client) => (bool success);
   ExitPresent();
-  SubmitFrame(VRPose? pose);
+  SubmitFrame(int16 frameId, gpu.mojom.MailboxHolder mailboxHolder);
   UpdateLayerBounds(int16 frameId, VRLayerBounds leftBounds,
-                    VRLayerBounds rightBounds);
+                    VRLayerBounds rightBounds, int16 sourceWidth,
+                    int16 sourceHeight);
   GetVRVSyncProvider(VRVSyncProvider& request);
 };
 
 interface VRVSyncProvider {
-  enum Status { SUCCESS, RETRY };
+  enum Status { SUCCESS, CLOSING };
 
   // The frameId maps a VSync to a frame arriving from the compositor. IDs will
   // be reused after the frame arrives from the compositor. Negative IDs imply