aw: Use comparison DCHECKs where appropriate

android_webview/browser/aw_login_delegate.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 "android_webview/browser/aw_login_delegate.h"
 
 #include "android_webview/browser/aw_browser_context.h"
 #include "base/android/jni_android.h"
 #include "base/logging.h"
 #include "base/supports_user_data.h"
@@ skipping 46 matching lines @@
 
     BrowserThread::PostTask(BrowserThread::UI, FROM_HERE,
         base::Bind(&AwLoginDelegate::HandleHttpAuthRequestOnUIThread,
                    this, (count->auth_attempts_ == 0)));
     count->auth_attempts_++;
 }
 
 AwLoginDelegate::~AwLoginDelegate() {
   // The Auth handler holds a ref count back on |this| object, so it should be
   // impossible to reach here while this object still owns an auth handler.
-  DCHECK(aw_http_auth_handler_ == NULL);
+  DCHECK(!aw_http_auth_handler_);
 }
 
 void AwLoginDelegate::Proceed(const base::string16& user,
                               const base::string16& password) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   BrowserThread::PostTask(BrowserThread::IO, FROM_HERE,
       base::Bind(&AwLoginDelegate::ProceedOnIOThread,
                  this, user, password));
 }
 
@@ skipping 50 matching lines @@
 void AwLoginDelegate::DeleteAuthHandlerSoon() {
   if (!BrowserThread::CurrentlyOn(BrowserThread::UI)) {
     BrowserThread::PostTask(BrowserThread::UI, FROM_HERE,
         base::Bind(&AwLoginDelegate::DeleteAuthHandlerSoon, this));
     return;
   }
   aw_http_auth_handler_.reset();
 }
 
 }  // namespace android_webview