Use ThreadSafeSender in a couple of places.

content/common/child_thread.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/common/child_thread.h"
 
 #include "base/allocator/allocator_extension.h"
 #include "base/command_line.h"
 #include "base/message_loop.h"
 #include "base/process.h"
@@ skipping 310 matching lines @@
 void ChildThread::OnGetTcmallocStats() {
   std::string result;
   char buffer[1024 * 32];
   base::allocator::GetStats(buffer, sizeof(buffer));
   result.append(buffer);
   Send(new ChildProcessHostMsg_TcmallocStats(result));
 }
 #endif
 
 ChildThread* ChildThread::current() {
-  return ChildProcess::current()->main_thread();
+  return ChildProcess::current() ?
+      ChildProcess::current()->main_thread() : NULL;
 }
 
 bool ChildThread::IsWebFrameValid(WebKit::WebFrame* frame) {
   // Return false so that it is overridden in any process in which it is used.
   return false;
 }
 
 void ChildThread::OnProcessFinalRelease() {
   if (on_channel_error_called_) {
     MessageLoop::current()->Quit();
     return;
   }
 
   // The child process shutdown sequence is a request response based mechanism,
   // where we send out an initial feeler request to the child process host
   // instance in the browser to verify if it's ok to shutdown the child process.
   // The browser then sends back a response if it's ok to shutdown. This avoids
   // race conditions if the process refcount is 0 but there's an IPC message
   // inflight that would addref it.
   Send(new ChildProcessHostMsg_ShutdownRequest);
 }
 
 void ChildThread::EnsureConnected() {
   LOG(INFO) << "ChildThread::EnsureConnected()";
   base::KillProcess(base::GetCurrentProcessHandle(), 0, false);
 }
 
 }  // namespace content