[Offline pages] Add null pointer checks in offline internals code

chrome/browser/ui/webui/offline/offline_internals_ui.cc

 // Copyright 2016 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/ui/webui/offline/offline_internals_ui.h"
 
 #include "base/macros.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/webui/offline/offline_internals_ui_message_handler.h"
 #include "chrome/common/url_constants.h"
@@ skipping 11 matching lines @@
   // Required resources.
   html_source->SetJsonPath("strings.js");
   html_source->AddResourcePath("offline_internals.css",
                                IDR_OFFLINE_INTERNALS_CSS);
   html_source->AddResourcePath("offline_internals.js",
                                IDR_OFFLINE_INTERNALS_JS);
   html_source->AddResourcePath("offline_internals_browser_proxy.js",
                                IDR_OFFLINE_INTERNALS_BROWSER_PROXY_JS);
   html_source->SetDefaultResource(IDR_OFFLINE_INTERNALS_HTML);
 
-  content::WebUIDataSource::Add(Profile::FromWebUI(web_ui), html_source);
+  Profile* profile = Profile::FromWebUI(web_ui);
+  html_source->AddBoolean("isIncognito", profile->IsOffTheRecord());
+
+  content::WebUIDataSource::Add(profile, html_source);
 
   web_ui->AddMessageHandler(
       new offline_internals::OfflineInternalsUIMessageHandler());
 }
 
 OfflineInternalsUI::~OfflineInternalsUI() {}