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

chrome/browser/android/vr_shell/non_presenting_gvr_delegate.h

Index: chrome/browser/android/vr_shell/non_presenting_gvr_delegate.h
diff --git a/chrome/browser/android/vr_shell/non_presenting_gvr_delegate.h b/chrome/browser/android/vr_shell/non_presenting_gvr_delegate.h
index 0bf91043cc56fa11d6e7f6a99fb736c39cc07d81..741b5d515a8069daa70e10d2cf15b1584447d330 100644
--- a/chrome/browser/android/vr_shell/non_presenting_gvr_delegate.h
+++ b/chrome/browser/android/vr_shell/non_presenting_gvr_delegate.h
@@ -28,10 +28,12 @@ class NonPresentingGvrDelegate : public device::GvrDelegate,
 
   // GvrDelegate implementation
   void SetWebVRSecureOrigin(bool secure_origin) override {}
-  void SubmitWebVRFrame() override {}
+  void SubmitWebVRFrame(int16_t frame_index,
+                        const gpu::MailboxHolder& mailbox) override {}
   void UpdateWebVRTextureBounds(int16_t frame_index,
                                 const gvr::Rectf& left_bounds,
-                                const gvr::Rectf& right_bounds) override {}
+                                const gvr::Rectf& right_bounds,
+                                const gvr::Sizei& source_size) override {}
   void OnVRVsyncProviderRequest(
       device::mojom::VRVSyncProviderRequest request) override;
   void UpdateVSyncInterval(int64_t timebase_nanos,