Revert "Revert"Adding a WindowAndroidHelper class"

chrome/browser/android/tab_android.cc

 // 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.
 
 #include "chrome/browser/android/tab_android.h"
+#include "chrome/browser/ui/android/window_android_helper.h"
 #include "chrome/browser/ui/tab_contents/tab_contents.h"
 #include "content/public/browser/android/content_view_core.h"
 #include "content/public/browser/web_contents.h"
 
-
 TabContents* TabAndroid::GetOrCreateTabContents(
     content::WebContents* web_contents) {
   TabContents* tab_contents = TabContents::FromWebContents(web_contents);
-  return tab_contents ? tab_contents : TabContents::Factory::CreateTabContents(
-      web_contents);
+  if (!tab_contents) {
+    tab_contents = TabContents::Factory::CreateTabContents(web_contents);
+    InitTabHelpers(web_contents);
+  }
+  return tab_contents;
+}
+
+void TabAndroid::InitTabHelpers(content::WebContents* web_contents) {
+  WindowAndroidHelper::CreateForWebContents(web_contents);
 }
 
 TabContents* TabAndroid::InitTabContentsFromView(JNIEnv* env,
                                                  jobject content_view) {
   content::ContentViewCore* content_view_core =
       content::ContentViewCore::GetNativeContentViewCore(env, content_view);
   DCHECK(content_view_core);
   DCHECK(content_view_core->GetWebContents());
   return GetOrCreateTabContents(content_view_core->GetWebContents());
 }
 
 TabAndroid::TabAndroid() : tab_id_(-1) {
 }
 
 TabAndroid::~TabAndroid() {
 }