Revert of Unify desktop and Android tab helper instantiation.

chrome/browser/ui/tab_helpers.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_TAB_HELPERS_H_
-#define CHROME_BROWSER_UI_TAB_HELPERS_H_
-
-namespace content {
-class WebContents;
-}
-
-namespace chrome {
-class BrowserTabStripModelDelegate;
-
-namespace android {
-class ChromeWebContentsDelegateAndroid;
-}
-}
-
-namespace prerender {
-class PrerenderContents;
-}
-
-// A "tab contents" is a WebContents that is used as a tab in a browser window
-// (or the equivalent on Android). The TabHelpers class allows specific classes
-// to attach the set of tab helpers that is used for tab contents.
-//
-// TODO(avi): This list is rather large, and for most callers it's due to the
-// fact that they need tab helpers attached early to deal with arbitrary
-// content loaded into a WebContents that will later be added to the tabstrip.
-// Is there a better way to handle this? (Ideally, this list would contain
-// only Browser and BrowserTabStripModelDelegate.)
-class TabHelpers {
- private:
-  // Browser and its TabStripModelDelegate have intimate control of tabs.
-  // TabAndroid is the equivalent on Android.
-  friend class Browser;
-  friend class chrome::BrowserTabStripModelDelegate;
-
-  // These are the Android equivalents of the two classes above.
-  friend class TabAndroid;
-  friend class chrome::android::ChromeWebContentsDelegateAndroid;
-
-  // chrome::Navigate creates WebContents that are destined for the tab strip,
-  // and that might have WebUI that immediately calls back into random tab
-  // helpers.
-  friend class BrowserNavigatorWebContentsAdoption;
-
-  // Prerendering loads pages that have arbitrary external content; it needs
-  // the full set of tab helpers to deal with it.
-  friend class prerender::PrerenderContents;
-
-  // Adopts the specified WebContents as a full-fledged browser tab, attaching
-  // all the associated tab helpers that are needed for the WebContents to
-  // serve in that role. It is safe to call this on a WebContents that was
-  // already adopted.
-  static void AttachTabHelpers(content::WebContents* web_contents);
-};
-
-#endif  // CHROME_BROWSER_UI_TAB_HELPERS_H_