Switch guest profile from forced-incognito to UI mods like ChromeOS.

chrome/browser/extensions/chrome_extensions_browser_client.cc

 // Copyright 2013 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/extensions/chrome_extensions_browser_client.h"
 
 #include "base/command_line.h"
 #include "base/version.h"
 #include "chrome/browser/app_mode/app_mode_utils.h"
 #include "chrome/browser/browser_process.h"
@@ skipping 102 matching lines @@
 #else
   // There are no browser windows open and the browser process was
   // started to show the app launcher.
   return chrome::GetTotalBrowserCountForProfile(profile) == 0 &&
          CommandLine::ForCurrentProcess()->HasSwitch(switches::kShowAppList);
 #endif
 }
 
 bool ChromeExtensionsBrowserClient::IsBackgroundPageAllowed(
     content::BrowserContext* context) const {
-#if defined(OS_CHROMEOS)
-  // Returns true if current session is Chrome OS Guest mode session and current
+  // Returns true if current session is Guest mode session and current
   // browser context is *not* off-the-record. Such context is artificial and
   // background page shouldn't be created in it.
-  const CommandLine* command_line = CommandLine::ForCurrentProcess();
-  if (command_line->HasSwitch(chromeos::switches::kGuestSession) &&
+  if ((static_cast<Profile*>(context))->IsGuestSession() &&

[msw, 2014/02/15 00:30:52]

nit: convert this if statement and following return to:
return !Profile::FromBrowserContext(context)->IsGuestSession() ||
context->IsOffTheRecord();

[bcwhite, 2014/02/18 15:19:36]

Done.

       !context->IsOffTheRecord()) {
     return false;
   }
-#endif
+
   return true;
 }
 
 void ChromeExtensionsBrowserClient::OnExtensionHostCreated(
     content::WebContents* web_contents) {
   PrefsTabHelper::CreateForWebContents(web_contents);
 }
 
 void ChromeExtensionsBrowserClient::OnRenderViewCreatedForBackgroundPage(
     ExtensionHost* host) {
@@ skipping 61 matching lines @@
   dependencies.push_back(ExtensionSystemSharedFactory::GetInstance());
   return dependencies;
 }
 
 ExtensionSystem* ChromeExtensionsBrowserClient::CreateExtensionSystem(
     content::BrowserContext* context) {
   return new ExtensionSystemImpl(static_cast<Profile*>(context));
 }
 
 }  // namespace extensions