[iOS] ios/web no longer depends on content::BrowserThread.

ios/web/web_thread_impl.cc

 // Copyright 2014 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 "ios/web/web_thread_impl.h"
 
 #include <string>
 
 #include "base/atomicops.h"
 #include "base/bind.h"
@@ skipping 479 matching lines @@
 
   WebThreadGlobals& globals = g_globals.Get();
   base::AutoLock lock(globals.lock);
   base::Thread* thread = globals.threads[identifier];
   DCHECK(thread);
   base::MessageLoop* loop = thread->message_loop();
   return loop;
 }
 
 // static
-void WebThreadImpl::SetDelegate(ID identifier, WebThreadDelegate* delegate) {
+void WebThread::SetDelegate(ID identifier, WebThreadDelegate* delegate) {
   using base::subtle::AtomicWord;
   WebThreadGlobals& globals = g_globals.Get();
   AtomicWord* storage =
       reinterpret_cast<AtomicWord*>(&globals.thread_delegates[identifier]);
   AtomicWord old_pointer = base::subtle::NoBarrier_AtomicExchange(
       storage, reinterpret_cast<AtomicWord>(delegate));
 
   // This catches registration when previously registered.
   DCHECK(!delegate || !old_pointer);
 }
 
 }  // namespace web