Revert "Revert"Adding a WindowAndroidHelper class"

chrome/browser/ui/android/window_android_helper.h

+// Copyright (c) 2012 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_UI_ANDROID_WINDOW_ANDROID_HELPER_H_
+#define CHROME_BROWSER_UI_ANDROID_WINDOW_ANDROID_HELPER_H_
+
+#include "content/public/browser/web_contents_user_data.h"
+
+namespace ui {
+class WindowAndroid;
+}
+
+// Per-tab class to provide access to WindowAndroid object.
+class WindowAndroidHelper
+    : public content::WebContentsUserData<WindowAndroidHelper> {
+ public:
+  virtual ~WindowAndroidHelper();
+
+  void SetWindowAndroid(ui::WindowAndroid* window_android);
+  ui::WindowAndroid* GetWindowAndroid();
+
+ private:
+  explicit WindowAndroidHelper(content::WebContents* web_contents);
+  friend class content::WebContentsUserData<WindowAndroidHelper>;
+
+  // The owning window that has a hold of main application activity.
+  ui::WindowAndroid* window_android_;
+
+  DISALLOW_COPY_AND_ASSIGN(WindowAndroidHelper);
+};
+
+#endif  // CHROME_BROWSER_UI_ANDROID_WINDOW_ANDROID_HELPER_H_