correct comment on GetTabManager

chrome/browser/browser_process.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.
 
 // This interface is for managing the global services of the application. Each
 // service is lazily created when requested the first time. The service getters
 // will return NULL if the service is not available, so callers must check for
 // this condition.
 
 #ifndef CHROME_BROWSER_BROWSER_PROCESS_H_
@@ skipping 251 matching lines @@
   virtual bool created_local_state() const = 0;
 
 #if defined(ENABLE_WEBRTC)
   virtual WebRtcLogUploader* webrtc_log_uploader() = 0;
 #endif
 
   virtual network_time::NetworkTimeTracker* network_time_tracker() = 0;
 
   virtual gcm::GCMDriver* gcm_driver() = 0;
 
-  // Returns the tab manager if it exists, null otherwise.
+  // Returns the tab manager. On non-supported platforms, this returns null.
   virtual memory::TabManager* GetTabManager() = 0;
 
   // Returns the default web client state of Chrome (i.e., was it the user's
   // default browser) at the time a previous check was made sometime between
   // process startup and now.
   virtual shell_integration::DefaultWebClientState
   CachedDefaultWebClientState() = 0;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(BrowserProcess);
 };
 
 extern BrowserProcess* g_browser_process;
 
 #endif  // CHROME_BROWSER_BROWSER_PROCESS_H_