DevTools: prepare workers for DevToolsManager::Attach(Detach)ClientHost removal.

content/browser/devtools/devtools_agent_host.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/devtools/devtools_agent_host.h"
 
 #include "base/basictypes.h"
 #include "content/common/devtools_messages.h"
 
 namespace content {
@@ skipping 29 matching lines @@
 }
 
 void DevToolsAgentHost::AddMessageToConsole(ConsoleMessageLevel level,
                                             const std::string& message) {
   SendMessageToAgent(new DevToolsAgentMsg_AddMessageToConsole(
       MSG_ROUTING_NONE,
       level,
       message));
 }
 
-void DevToolsAgentHost::NotifyCloseListener() {
+bool DevToolsAgentHost::NotifyCloseListener() {
   if (close_listener_) {
     close_listener_->AgentHostClosing(this);
     close_listener_ = NULL;
+    return true;
   }
+  return false;
 }
 
 }  // namespace content