Fix lock-order-inversion in ChannelMojo

ipc/mojo/ipc_channel_mojo.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 "ipc/mojo/ipc_channel_mojo.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <memory>
@@ skipping 222 matching lines @@
   // ChannelMojo from a different thread.
   bootstrap_ = MojoBootstrap::Create(std::move(handle), mode, this);
 }
 
 ChannelMojo::~ChannelMojo() {
   Close();
 }
 
 bool ChannelMojo::Connect() {
   WillConnect();
-  base::AutoLock lock(lock_);
-  DCHECK(!task_runner_);
-  task_runner_ = base::ThreadTaskRunnerHandle::Get();
-  DCHECK(!message_reader_);
+  {
+    base::AutoLock lock(lock_);
+    DCHECK(!task_runner_);
+    task_runner_ = base::ThreadTaskRunnerHandle::Get();
+    DCHECK(!message_reader_);
+  }
   bootstrap_->Connect();
   return true;
 }
 
 void ChannelMojo::Close() {
   std::unique_ptr<internal::MessagePipeReader, ReaderDeleter> reader;
   {
     base::AutoLock lock(lock_);
     if (!message_reader_)
       return;
@@ skipping 172 matching lines @@
     DCHECK(ok);
     if (!ok) {
       LOG(ERROR) << "Failed to add new Mojo handle.";
       return MOJO_RESULT_UNKNOWN;
     }
   }
   return MOJO_RESULT_OK;
 }
 
 }  // namespace IPC