Allow VRDisplay to specify which frame the layer bounds should be updated at.

chrome/browser/android/vr_shell/vr_shell_gl.cc

Index: chrome/browser/android/vr_shell/vr_shell_gl.cc
diff --git a/chrome/browser/android/vr_shell/vr_shell_gl.cc b/chrome/browser/android/vr_shell/vr_shell_gl.cc
index effea8744a33b0116316f64481f8d79c751d5497..e372479264219fcf9db1e5b2b4d0c2192d9c17fb 100644
--- a/chrome/browser/android/vr_shell/vr_shell_gl.cc
+++ b/chrome/browser/android/vr_shell/vr_shell_gl.cc
@@ -934,8 +934,11 @@ void VrShellGl::SetWebVrMode(bool enabled) {
   web_vr_mode_ = enabled;
 }
 
-void VrShellGl::UpdateWebVRTextureBounds(const gvr::Rectf& left_bounds,
+void VrShellGl::UpdateWebVRTextureBounds(uint32_t frame_index,
+                                         const gvr::Rectf& left_bounds,
                                          const gvr::Rectf& right_bounds) {
+  // TODO(klausw): Only update the texture bounds once we're rendering frame
+  // |for_frame_index|.

[dcheng, 2017/01/10 06:53:19]

Sorry for missing this in my review queue. Is there any way to upstream the IPC
changes with the complete implementation changes?

   webvr_left_viewport_->SetSourceUv(left_bounds);
   webvr_right_viewport_->SetSourceUv(right_bounds);
 }