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

chrome/browser/extensions/extension_system_impl.cc

 // Copyright 2014 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/extension_system_impl.h"
 
 #include "base/base_switches.h"
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/files/file_path.h"
@@ skipping 132 matching lines @@
   navigation_observer_.reset(new NavigationObserver(profile_));
 
   bool allow_noisy_errors = !command_line->HasSwitch(switches::kNoErrorDialogs);
   ExtensionErrorReporter::Init(allow_noisy_errors);
 
   user_script_master_ = new UserScriptMaster(profile_);
 
   // ExtensionService depends on RuntimeData.
   runtime_data_.reset(new RuntimeData(ExtensionRegistry::Get(profile_)));
 
-  bool autoupdate_enabled = true;
+  bool autoupdate_enabled = !profile_->IsGuestSession();
 #if defined(OS_CHROMEOS)
   if (!extensions_enabled)
     autoupdate_enabled = false;
-  else
-    autoupdate_enabled =
-        !command_line->HasSwitch(chromeos::switches::kGuestSession);
 #endif
   extension_service_.reset(new ExtensionService(
       profile_,
       CommandLine::ForCurrentProcess(),
       profile_->GetPath().AppendASCII(extensions::kInstallDirectoryName),
       ExtensionPrefs::Get(profile_),
       blacklist_.get(),
       autoupdate_enabled,
       extensions_enabled,
       &ready_));
@@ skipping 267 matching lines @@
 void ExtensionSystemImpl::UnregisterExtensionWithRequestContexts(
     const std::string& extension_id,
     const UnloadedExtensionInfo::Reason reason) {
   BrowserThread::PostTask(
       BrowserThread::IO,
       FROM_HERE,
       base::Bind(&InfoMap::RemoveExtension, info_map(), extension_id, reason));
 }
 
 }  // namespace extensions