Fifth patch in getting rid of caching MessageLoop pointers.

chrome/browser/chrome_thread.cc

 // Copyright (c) 2009 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/chrome_thread.h"
 
 // Friendly names for the well-known threads.
 static const char* chrome_thread_names[ChromeThread::ID_COUNT] = {
   "",  // UI (name assembled in browser_main.cc).
   "Chrome_DBThread",  // DB
@@ skipping 36 matching lines @@
   // Double check that the threads are ordererd correctly in the enumeration.
   for (int i = identifier_ + 1; i < ID_COUNT; ++i) {
     DCHECK(!chrome_threads_[i]) <<
         "Threads must be listed in the reverse order that they die";
   }
 #endif
 }
 
 // static
 bool ChromeThread::CurrentlyOn(ID identifier) {
-  // chrome_threads_[identifier] will be NULL if none is running.  This is often
-  // true when running under unit tests.  This behavior actually works out
-  // pretty conveniently but it's worth noting here.
   AutoLock lock(lock_);
   DCHECK(identifier >= 0 && identifier < ID_COUNT);
   return chrome_threads_[identifier] &&
          chrome_threads_[identifier]->message_loop() == MessageLoop::current();
 }
 
 // static
 bool ChromeThread::PostTask(ID identifier,
                             const tracked_objects::Location& from_here,
                             Task* task) {
@@ skipping 71 matching lines @@
     }
   } else {
     delete task;
   }
 
   if (!guaranteed_to_outlive_target_thread)
     lock_.Release();
 
   return !!message_loop;
 }