Disable MessageLoop features on some BrowserThreads.

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.h>
 
 #include <string>
 
@@ skipping 167 matching lines @@
   // We don't want to create a pool if none exists.
   if (g_globals == nullptr)
     return;
   g_globals.Get().blocking_pool->FlushForTesting();
   disk_cache::SimpleBackendImpl::FlushWorkerPoolForTesting();
 }
 
 void BrowserThreadImpl::Init() {
   BrowserThreadGlobals& globals = g_globals.Get();
 
+  if (BrowserThread::CurrentlyOn(BrowserThread::DB) ||
+      BrowserThread::CurrentlyOn(BrowserThread::FILE) ||
+      BrowserThread::CurrentlyOn(BrowserThread::FILE_USER_BLOCKING) ||
+      BrowserThread::CurrentlyOn(BrowserThread::PROCESS_LAUNCHER) ||
+      BrowserThread::CurrentlyOn(BrowserThread::CACHE)) {
+    base::MessageLoop* message_loop = base::MessageLoop::current();
+    message_loop->DisableNesting();
+    message_loop->DisableDestructionObservers();
+    message_loop->DisableTaskObservers();
+  }
+
   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)
     delegate->Init();
 }
 
@@ skipping 384 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