Fix crash in PluginService if the keys are null. It's still unclear why this...

chrome/browser/plugin_service.cc

 // Copyright (c) 2010 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 "chrome/browser/plugin_service.h"
 
 #include <vector>
 
 #include "base/command_line.h"
 #include "base/path_service.h"
@@ skipping 200 matching lines @@
 #endif
   registrar_.Add(this, NotificationType::PLUGIN_ENABLE_STATUS_CHANGED,
                  NotificationService::AllSources());
 }
 
 PluginService::~PluginService() {
 #if defined(OS_WIN)
   // Release the events since they're owned by RegKey, not WaitableEvent.
   hkcu_watcher_.StopWatching();
   hklm_watcher_.StopWatching();
-  hkcu_event_->Release();
-  hklm_event_->Release();
+  if (hkcu_event_.get())
+    hkcu_event_->Release();
+  if (hklm_event_.get())
+    hklm_event_->Release();
 #endif
 }
 
 void PluginService::LoadChromePlugins(
     ResourceDispatcherHost* resource_dispatcher_host) {
   if (!enable_chrome_plugins_)
     return;
 
   resource_dispatcher_host_ = resource_dispatcher_host;
   ChromePluginLib::LoadChromePlugins(GetCPBrowserFuncsForBrowser());
@@ skipping 253 matching lines @@
 #if defined(OS_LINUX)
 // static
 void PluginService::RegisterFilePathWatcher(
     FilePathWatcher *watcher,
     const FilePath& path,
     FilePathWatcher::Delegate* delegate) {
   bool result = watcher->Watch(path, delegate);
   DCHECK(result);
 }
 #endif