Ensure that the web contents trying to access native VR Shell is the webcontents we created.

chrome/browser/ui/webui/vr_shell/vr_shell_ui_message_handler.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ui/webui/vr_shell/vr_shell_ui_message_handler.h"
 
 #include <memory>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/callback.h"
 #include "base/values.h"
 #include "chrome/browser/android/vr_shell/vr_shell.h"
 #include "content/public/browser/web_ui.h"
 
 VrShellUIMessageHandler::VrShellUIMessageHandler() {}
 
 VrShellUIMessageHandler::~VrShellUIMessageHandler() {}
 
 void VrShellUIMessageHandler::RegisterMessages() {
-  vr_shell_ = vr_shell::VrShell::GetWeakPtr();
+  vr_shell_ = vr_shell::VrShell::GetWeakPtr(web_ui()->GetWebContents());
 
   web_ui()->RegisterMessageCallback(
       "domLoaded", base::Bind(&VrShellUIMessageHandler::HandleDomLoaded,
                               base::Unretained(this)));
   web_ui()->RegisterMessageCallback(
       "updateScene", base::Bind(&VrShellUIMessageHandler::HandleUpdateScene,
                             base::Unretained(this)));
   web_ui()->RegisterMessageCallback(
       "doAction", base::Bind(&VrShellUIMessageHandler::HandleDoAction,
                              base::Unretained(this)));
@@ skipping 21 matching lines @@
   auto cb = base::Bind(&vr_shell::UiScene::HandleCommands,
                        base::Unretained(vr_shell_->GetScene()),
                        base::Owned(args->CreateDeepCopy().release()),
                        vr_shell::UiScene::TimeInMicroseconds());
   vr_shell_->QueueTask(cb);
 }
 
 void VrShellUIMessageHandler::HandleDoAction(const base::ListValue* args) {
   NOTIMPLEMENTED();
 }