Lazily initialize MessageLoop for faster thread startup

content/browser/browser_thread_impl.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 "content/browser/browser_thread_impl.h"
 
 #include <string>
 
 #include "base/atomicops.h"
 #include "base/bind.h"
@@ skipping 141 matching lines @@
 
 void BrowserThreadImpl::Init() {
   BrowserThreadGlobals& globals = g_globals.Get();
 
   using base::subtle::AtomicWord;
   AtomicWord* storage =
       reinterpret_cast<AtomicWord*>(&globals.thread_delegates[identifier_]);
   AtomicWord stored_pointer = base::subtle::NoBarrier_Load(storage);
   BrowserThreadDelegate* delegate =
       reinterpret_cast<BrowserThreadDelegate*>(stored_pointer);
-  if (delegate) {
+  if (delegate)
     delegate->Init();
-    message_loop()->PostTask(FROM_HERE,
-                             base::Bind(&BrowserThreadDelegate::InitAsync,
-                                        // Delegate is expected to exist for the
-                                        // duration of the thread's lifetime
-                                        base::Unretained(delegate)));
-  }
 }
 
 // We disable optimizations for this block of functions so the compiler doesn't
 // merge them all together.
 MSVC_DISABLE_OPTIMIZE()
 MSVC_PUSH_DISABLE_WARNING(4748)
 
 NOINLINE void BrowserThreadImpl::UIThreadRun(base::MessageLoop* message_loop) {
   volatile int line_number = __LINE__;
   Thread::Run(message_loop);
@@ skipping 360 matching lines @@
   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 content