Multiple sync channels if used in the same listener thread could result in ca...

chrome/browser/renderer_host/browser_render_process_host.cc

 // Copyright (c) 2009 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.
 
 // Represents the browser side of the browser <--> renderer communication
 // channel. There will be one RenderProcessHost per renderer process.
 
 #include "chrome/browser/renderer_host/browser_render_process_host.h"
 
 #include "build/build_config.h"
@@ skipping 868 matching lines @@
     // In single process mode it is better if we don't suicide but just crash.
     CHECK(false);
   }
   NOTREACHED();
   base::KillProcess(process, ResultCodes::KILLED_BAD_MESSAGE, false);
 }
 
 void BrowserRenderProcessHost::OnChannelError() {
   // Our child process has died.  If we didn't expect it, it's a crash.
   // In any case, we need to let everyone know it's gone.
-  DCHECK(channel_.get());
+  // The OnChannelError notification can fire multiple times due to nested sync
+  // calls to a renderer. If we don't have a valid channel here it means we
+  // already handled the error.
+  if (!channel_.get())
+    return;
 
   bool child_exited;
   bool did_crash;
   if (!process_.handle()) {
     // The process has been terminated (likely FastShutdownIfPossible).
     did_crash = false;
     child_exited = true;
   } else if (zygote_child_) {
 #if defined(OS_LINUX)
     did_crash = Singleton<ZygoteHost>()->DidProcessCrash(
@@ skipping 123 matching lines @@
     profile()->GetExtensionMessageService()->RemoveEventListener(
         event_name, id());
   }
 }
 
 void BrowserRenderProcessHost::OnExtensionCloseChannel(int port_id) {
   if (profile()->GetExtensionMessageService()) {
     profile()->GetExtensionMessageService()->CloseChannel(port_id);
   }
 }