Stop setting invalid value to the |tab_id| field of fileBrowserHandler API.

chrome/browser/chromeos/extensions/file_manager/private_api_util.cc

 // Copyright 2013 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/chromeos/extensions/file_manager/private_api_util.h"
 
 #include "base/files/file_path.h"
 #include "chrome/browser/chromeos/drive/drive.pb.h"
 #include "chrome/browser/chromeos/drive/file_errors.h"
 #include "chrome/browser/chromeos/drive/file_system_interface.h"
@@ skipping 217 matching lines @@
   }
   content::WebContents* web_contents =
       dispatcher->delegate()->GetAssociatedWebContents();
   if (!web_contents) {
     LOG(WARNING) << "No associated tab contents";
     return NULL;
   }
   return web_contents;
 }
 
-int32 GetTabId(ExtensionFunctionDispatcher* dispatcher) {
-  content::WebContents* web_contents = GetWebContents(dispatcher);
-  return web_contents ?
-      extensions::ExtensionTabUtil::GetTabId(web_contents) : 0;
-}
-
 base::FilePath GetLocalPathFromURL(
     content::RenderViewHost* render_view_host,
     Profile* profile,
     const GURL& url) {
   DCHECK(render_view_host);
   DCHECK(profile);
 
   scoped_refptr<fileapi::FileSystemContext> file_system_context =
       util::GetFileSystemContextForRenderViewHost(
           profile, render_view_host);
@@ skipping 30 matching lines @@
 
   BrowserThread::PostTask(
       BrowserThread::UI, FROM_HERE,
       base::Bind(&GetSelectedFileInfoInternal,
                  profile,
                  base::Passed(&params)));
 }
 
 }  // namespace util
 }  // namespace file_manager