Remove all but one use of WeakPtrFactory::DetachFromThread.

chrome/browser/io_thread.cc

 // 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.
 
 #include "chrome/browser/io_thread.h"
 
 #include <vector>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
@@ skipping 566 matching lines @@
   // Note that since we are at BrowserThread::Init time, the UI thread
   // is blocked waiting for the thread to start.  Therefore, posting
   // this task to the main thread's message loop here is guaranteed to
   // get it onto the message loop while the IOThread object still
   // exists.  However, the message might not be processed on the UI
   // thread until after IOThread is gone, so use a weak pointer.
   BrowserThread::PostTask(BrowserThread::UI,
                           FROM_HERE,
                           base::Bind(&IOThread::InitSystemRequestContext,
                                      weak_factory_.GetWeakPtr()));
-
-  // We constructed the weak pointer on the IO thread but it will be
-  // used on the UI thread.  Call this to avoid a thread checker
-  // error.
-  weak_factory_.DetachFromThread();
 }
 
 void IOThread::CleanUp() {
   base::debug::LeakTracker<SafeBrowsingURLRequestContext>::CheckForLeaks();
 
   delete sdch_manager_;
   sdch_manager_ = NULL;
 
 #if defined(USE_NSS) || defined(OS_IOS)
   net::ShutdownNSSHttpIO();
@@ skipping 311 matching lines @@
   globals_->system_request_context.reset(
       ConstructSystemRequestContext(globals_, net_log_));
 
   sdch_manager_->set_sdch_fetcher(
       new SdchDictionaryFetcher(system_url_request_context_getter_.get()));
 }
 
 void IOThread::UpdateDnsClientEnabled() {
   globals()->host_resolver->SetDnsClientEnabled(*dns_client_enabled_);
 }