Revert making HandleWatcher block until no longer waiting on pipe (r285266).

base/threading/thread_restrictions.h

 // 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.
 
 #ifndef BASE_THREADING_THREAD_RESTRICTIONS_H_
 #define BASE_THREADING_THREAD_RESTRICTIONS_H_
 
 #include "base/base_export.h"
 #include "base/basictypes.h"
 
@@ skipping 37 matching lines @@
 namespace dbus {
 class Bus;
 }
 namespace disk_cache {
 class BackendImpl;
 class InFlightIO;
 }
 namespace gles2 {
 class CommandBufferClientImpl;
 }
-namespace mojo {
-namespace common {
-class WatcherThreadManager;
-}
-}
 namespace net {
 class NetworkChangeNotifierMac;
 namespace internal {
 class AddressTrackerLinux;
 }
 }
 
 namespace remoting {
 class AutoThread;
 }
@@ skipping 112 matching lines @@
   // BEGIN ALLOWED USAGE.
   friend class content::BrowserShutdownProfileDumper;
   friend class content::BrowserTestBase;
   friend class content::NestedMessagePumpAndroid;
   friend class content::ScopedAllowWaitForAndroidLayoutTests;
   friend class content::ScopedAllowWaitForDebugURL;
   friend class ::HistogramSynchronizer;
   friend class ::ScopedAllowWaitForLegacyWebViewApi;
   friend class cc::CompletionEvent;
   friend class cc::TaskGraphRunner;
-  friend class mojo::common::WatcherThreadManager;
   friend class remoting::AutoThread;
   friend class ui::WindowResizeHelperMac;
   friend class MessagePumpDefault;
   friend class SequencedWorkerPool;
   friend class SimpleThread;
   friend class Thread;
   friend class ThreadTestHelper;
   friend class PlatformThread;
   friend class android::JavaHandlerThread;
   friend class gles2::CommandBufferClientImpl;
@@ skipping 43 matching lines @@
 
     DISALLOW_COPY_AND_ASSIGN(ScopedAllowWait);
   };
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(ThreadRestrictions);
 };
 
 }  // namespace base
 
 #endif  // BASE_THREADING_THREAD_RESTRICTIONS_H_