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

chrome/browser/android/vr_shell/vr_shell.h

Index: chrome/browser/android/vr_shell/vr_shell.h
diff --git a/chrome/browser/android/vr_shell/vr_shell.h b/chrome/browser/android/vr_shell/vr_shell.h
index a95676ea6ce6316c07baf9a73a2cf074ca4cf434..b964a14c3aac5472d58d6ae2cb8480bbb2badf20 100644
--- a/chrome/browser/android/vr_shell/vr_shell.h
+++ b/chrome/browser/android/vr_shell/vr_shell.h
@@ -100,7 +100,8 @@ class VrShell : public device::GvrDelegate, content::WebContentsObserver {
   // called on the UI thread, but use GL thread objects in a non-threadsafe way.
   void SetWebVRSecureOrigin(bool secure_origin) override;
   void SubmitWebVRFrame() override;
-  void UpdateWebVRTextureBounds(const gvr::Rectf& left_bounds,
+  void UpdateWebVRTextureBounds(uint32_t frame_index,
+                                const gvr::Rectf& left_bounds,
                                 const gvr::Rectf& right_bounds) override;
   gvr::GvrApi* gvr_api() override;
   void SetGvrPoseForWebVr(const gvr::Mat4f& pose, uint32_t pose_num) override;