[Offline pages] Filter out pages cached by different tabs on tab helper

chrome/browser/android/offline_pages/offline_page_utils.h

 // Copyright 2015 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_OFFLINE_PAGES_OFFLINE_PAGE_UTILS_H_
 #define CHROME_BROWSER_ANDROID_OFFLINE_PAGES_OFFLINE_PAGE_UTILS_H_
 
 #include <stdint.h>
 
 #include "base/callback.h"
@@ skipping 42 matching lines @@
 
   // Marks that the offline page related to the |offline_url| has been accessed.
   static void MarkPageAccessed(content::BrowserContext* browser_context,
                                const GURL& offline_url);
 
   // Gets the offline page corresponding to the given web contents.  The
   // returned pointer is owned by the web_contents and may be deleted by user
   // navigation, so it is unsafe to store a copy of the returned pointer.
   static const OfflinePageItem* GetOfflinePageFromWebContents(
       content::WebContents* web_contents);
+
+  // Gets an Android Tab ID from a tab containing |web_contents|. Returns false,
+  // when tab is not available. Returns true otherwise and sets |tab_id| to the
+  // ID of the tab.
+  static bool GetTabId(content::WebContents* web_contents, int* tab_id);
 };
 
 }  // namespace offline_pages
 
 #endif  // CHROME_BROWSER_ANDROID_OFFLINE_PAGES_OFFLINE_PAGE_UTILS_H_