Implement our own GLThread for VR Shell.

chrome/browser/android/vr_shell/vr_web_contents_observer.cc

Index: chrome/browser/android/vr_shell/vr_web_contents_observer.cc
diff --git a/chrome/browser/android/vr_shell/vr_web_contents_observer.cc b/chrome/browser/android/vr_shell/vr_web_contents_observer.cc
index 7171937ddc6ff86e4f930e57ebadda49006585d7..d36a68cf80cd7b19057c826d4eff89eefc65354b 100644
--- a/chrome/browser/android/vr_shell/vr_web_contents_observer.cc
+++ b/chrome/browser/android/vr_shell/vr_web_contents_observer.cc
@@ -74,11 +74,15 @@ void VrWebContentsObserver::DidToggleFullscreenModeForTab(
 }
 
 void VrWebContentsObserver::WebContentsDestroyed() {
-  vr_shell_->ContentWebContentsDestroyedOnUI();
+  vr_shell_->ContentWebContentsDestroyed();
 }
 
 void VrWebContentsObserver::WasHidden() {
-  vr_shell_->ContentWasHiddenOnUI();
+  vr_shell_->ContentWasHidden();
+}
+
+void VrWebContentsObserver::MainFrameWasResized(bool width_changed) {
+  vr_shell_->ContentFrameWasResized(width_changed);
 }
 
 void VrWebContentsObserver::RenderViewHostChanged(