extensions::Dispatcher: Don't crash if forced_idle_timer_ is null.

extensions/renderer/dispatcher.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 "extensions/renderer/dispatcher.h"
 
 #include "base/callback.h"
 #include "base/command_line.h"
 #include "base/debug/alias.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 488 matching lines @@
 
     InitOriginPermissions(extension);
   }
 
   EnableCustomElementWhiteList();
 
   is_webkit_initialized_ = true;
 }
 
 void Dispatcher::IdleNotification() {
-  if (is_extension_process_) {
+  if (is_extension_process_ && forced_idle_timer_) {
     // Dampen the forced delay as well if the extension stays idle for long
-    // periods of time.
+    // periods of time. (forced_idle_timer_ can be NULL after
+    // OnRenderProcessShutdown has been called.)
     int64 forced_delay_ms =
         std::max(RenderThread::Get()->GetIdleNotificationDelayInMs(),
                  kMaxExtensionIdleHandlerDelayMs);
     forced_idle_timer_->Stop();
     forced_idle_timer_->Start(
         FROM_HERE,
         base::TimeDelta::FromMilliseconds(forced_delay_ms),
         RenderThread::Get(),
         &RenderThread::IdleHandler);
   }
@@ skipping 712 matching lines @@
     return v8::Handle<v8::Object>();
 
   if (bind_name)
     *bind_name = split.back();
 
   return bind_object.IsEmpty() ? AsObjectOrEmpty(GetOrCreateChrome(context))
                                : bind_object;
 }
 
 }  // namespace extensions