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

content/browser/devtools/devtools_manager_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/devtools/devtools_manager_impl.h"
 
 #include <vector>
 
 #include "base/bind.h"
 #include "base/message_loop.h"
@@ skipping 223 matching lines @@
   agent_to_client_host_.erase(agent_host);
   client_to_agent_host_.erase(client_host);
   agent_runtime_states_.erase(agent_host);
 
   if (client_to_agent_host_.empty()) {
     BrowserThread::PostTask(
         BrowserThread::IO,
         FROM_HERE,
         base::Bind(&DevToolsNetLogObserver::Detach));
   }
+  int process_id = agent_host->GetRenderProcessId();
+
+  // Lazy agent hosts can be deleted from within detach.
+  // Do not access agent_host below this line.
   agent_host->Detach();
 
-  int process_id = agent_host->GetRenderProcessId();
   if (process_id == -1)
     return;
   for (AgentToClientHostMap::iterator it = agent_to_client_host_.begin();
        it != agent_to_client_host_.end();
        ++it) {
     if (it->first->GetRenderProcessId() == process_id)
       return;
   }
   // We've disconnected from the last renderer -> revoke cookie permissions.
   ChildProcessSecurityPolicyImpl::GetInstance()->RevokeReadRawCookies(
       process_id);
 }
 
 void DevToolsManagerImpl::CloseAllClientHosts() {
   std::vector<DevToolsAgentHost*> agents;
   for (AgentToClientHostMap::iterator it =
            agent_to_client_host_.begin();
        it != agent_to_client_host_.end(); ++it) {
     agents.push_back(it->first);
   }
   for (std::vector<DevToolsAgentHost*>::iterator it = agents.begin();
        it != agents.end(); ++it) {
     UnregisterDevToolsClientHostFor(*it);
   }
 }
 
 }  // namespace content