Clean up VR Shell mode transitions (and fix potential webvr startup race).

chrome/browser/android/vr_shell/ui_interface.h

 // 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.
 
 #ifndef CHROME_BROWSER_ANDROID_VR_SHELL_UI_INTERFACE_H_
 #define CHROME_BROWSER_ANDROID_VR_SHELL_UI_INTERFACE_H_
 
 #include "base/macros.h"
 #include "base/values.h"
 
 class GURL;
 
 namespace vr_shell {
 
 class UiCommandHandler {
  public:
   virtual void SendCommandToUi(const base::Value& value) = 0;
 };
 
 // This class manages the communication of browser state from VR shell to the
 // HTML UI. State information is asynchronous and unidirectional.
 class UiInterface {
  public:
   enum Mode {
     STANDARD,
     WEB_VR,
-    MENU,
     CINEMA,
+    STANDARD_MENU,

[bshe, 2016/11/28 22:15:07]

nit: can you add comments about the two new enum? It is not obvious why we need
STARND and WEBVR menu be different.

[mthiesse, 2016/11/28 23:28:34]

Acknowledged.

+    WEB_VR_MENU,
   };
 
-  UiInterface();
+  explicit UiInterface(Mode initial_mode);
   virtual ~UiInterface();
 
   void SetMode(Mode mode);
   Mode GetMode() { return mode_; }
   void SetSecureOrigin(bool secure);
   void SetLoading(bool loading);
   void SetURL(const GURL& url);
 
   // Called by WebUI when starting VR.
   void OnDomContentsLoaded();
   void SetUiCommandHandler(UiCommandHandler* handler);
 
  private:
   void FlushUpdates();
 
   Mode mode_;
   UiCommandHandler* handler_;
   bool loaded_ = false;
   base::DictionaryValue updates_;
 
   DISALLOW_COPY_AND_ASSIGN(UiInterface);
 };
 
 }  // namespace vr_shell
 
 #endif  // CHROME_BROWSER_ANDROID_VR_SHELL_UI_INTERFACE_H_