Fix null pointer bug, add better logging to see why pointer is sometimes null.

chrome/browser/extensions/api/push_messaging/push_messaging_api.h

 // 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.
 
 #ifndef CHROME_BROWSER_EXTENSIONS_API_PUSH_MESSAGING_PUSH_MESSAGING_API_H__
 #define CHROME_BROWSER_EXTENSIONS_API_PUSH_MESSAGING_PUSH_MESSAGING_API_H__
 
 #include <string>
 
 #include "base/basictypes.h"
@@ skipping 73 matching lines @@
   bool IsUserLoggedIn() const;
 
   // ObfuscatedGiaiaIdFetcher::Delegate implementation.
   virtual void OnObfuscatedGaiaIdFetchSuccess(const std::string& gaia_id)
       OVERRIDE;
   virtual void OnObfuscatedGaiaIdFetchFailure(
       const GoogleServiceAuthError& error) OVERRIDE;
   scoped_ptr<ObfuscatedGaiaIdFetcher> fetcher_;
   bool interactive_;
 
-  // We use this to register for notifications if the logon attept succeeds.
+  // We use this to register for notifications if the login attempt succeeds.
   content::NotificationRegistrar registrar_;
 
   DISALLOW_COPY_AND_ASSIGN(PushMessagingGetChannelIdFunction);
 };
 
 class PushMessagingAPI : public ProfileKeyedAPI,
                          public content::NotificationObserver {
  public:
   explicit PushMessagingAPI(Profile* profile);
   virtual ~PushMessagingAPI();
@@ skipping 41 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(PushMessagingAPI);
 };
 
 template <>
 void ProfileKeyedAPIFactory<PushMessagingAPI>::DeclareFactoryDependencies();
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_PUSH_MESSAGING_PUSH_MESSAGING_API_H__