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

chrome/browser/android/vr_shell/vr_shell.cc

Index: chrome/browser/android/vr_shell/vr_shell.cc
diff --git a/chrome/browser/android/vr_shell/vr_shell.cc b/chrome/browser/android/vr_shell/vr_shell.cc
index ba595ae5bf5dd9ef7d0c95cf17f634cc532c5eb2..cdf96ea27dd0def7aaf0c77f1188d3df32c0032d 100644
--- a/chrome/browser/android/vr_shell/vr_shell.cc
+++ b/chrome/browser/android/vr_shell/vr_shell.cc
@@ -36,6 +36,7 @@
 #include "content/public/common/referrer.h"
 #include "device/vr/android/gvr/gvr_device.h"
 #include "device/vr/android/gvr/gvr_device_provider.h"
+#include "gpu/command_buffer/common/mailbox.h"
 #include "jni/VrShellImpl_jni.h"
 #include "third_party/WebKit/public/platform/WebInputEvent.h"
 #include "ui/android/view_android.h"
@@ -324,7 +325,24 @@ void VrShell::SetWebVRSecureOrigin(bool secure_origin) {
   html_interface_->SetWebVRSecureOrigin(secure_origin);
 }
 
-void VrShell::SubmitWebVRFrame() {}
+void VrShell::SubmitWebVRFrame(

[mthiesse, 2017/03/02 15:55:16]

In a future patch we should consider binding SubmitFrame directly to the GL
thread to skip this unnecessary hop.

[klausw, 2017/03/07 02:55:54]

Acknowledged.

+    int frame_index, const gpu::Mailbox& mailbox,
+    device::mojom::VRSubmitFrameClientPtr submit_client) {
+  PostToGlThreadWhenReady(base::Bind(&VrShellGl::SubmitWebVRFrame,
+                                     gl_thread_->GetVrShellGl(), frame_index,
+                                     mailbox));
+  webvr_submit_client_transferring_ = std::move(submit_client);
+}
+
+void VrShell::OnSubmitWebVRFrameTransferred(int frame_index) {
+  webvr_submit_client_transferring_->OnSubmitFrameTransferred();
+  webvr_submit_client_rendering_ = std::move(webvr_submit_client_transferring_);
+}
+
+void VrShell::OnSubmitWebVRFrameRendered(int frame_index) {
+  webvr_submit_client_rendering_->OnSubmitFrameRendered();
+  webvr_submit_client_rendering_.reset();
+}
 
 void VrShell::UpdateWebVRTextureBounds(int16_t frame_index,
                                        const gvr::Rectf& left_bounds,