Fix the System Profile to not load extensions. It could otherwise be forced to by GPO.

chrome/browser/app_controller_mac.mm

 // 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.
 
 #import "chrome/browser/app_controller_mac.h"
 
 #include "base/auto_reset.h"
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/files/file_path.h"
@@ skipping 1014 matching lines @@
   // Ignore commands during session restore's browser creation.  It uses a
   // nested message loop and commands dispatched during this operation cause
   // havoc.
   if (SessionRestore::IsRestoring(lastProfile) &&
       base::MessageLoop::current()->IsNested())
     return;
 
   NSInteger tag = [sender tag];
 
   // If there are no browser windows, and we are trying to open a browser
-  // for a locked profile, we have to show the User Manager instead as the
-  // locked profile needs authentication.
-  if (IsProfileSignedOut(lastProfile)) {
+  // for a locked profile or the system profile, we have to show the User
+  // Manager instead as the locked profile needs authentication and the system
+  // profile cannot have a browser.
+  if (IsProfileSignedOut(lastProfile) || lastProfile->IsSystemProfile()) {
     UserManager::Show(base::FilePath(),
                       profiles::USER_MANAGER_NO_TUTORIAL,
                       profiles::USER_MANAGER_SELECT_PROFILE_NO_ACTION);
     return;
   }
 
   switch (tag) {
     case IDC_NEW_TAB:
       // Create a new tab in an existing browser window (which we activate) if
       // possible.
@@ skipping 191 matching lines @@
           SessionServiceFactory::GetForProfileForSessionRestore(
               [self lastProfile]);
       if (sessionService &&
           sessionService->RestoreIfNecessary(std::vector<GURL>()))
         return NO;
     }
   }
 
   // Otherwise open a new window.
   // If the last profile was locked, we have to open the User Manager, as the
-  // profile requires authentication. Similarly, because guest mode is
-  // implemented as forced incognito, we can't open a new guest browser either,
-  // so we have to show the User Manager as well.
+  // profile requires authentication. Similarly, because guest mode and system
+  // profile are implemented as forced incognito, we can't open a new guest
+  // browser either, so we have to show the User Manager as well.
   Profile* lastProfile = [self lastProfile];
-  if (lastProfile->IsGuestSession() || IsProfileSignedOut(lastProfile)) {
+  if (lastProfile->IsGuestSession() || IsProfileSignedOut(lastProfile) ||
+      lastProfile->IsSystemProfile()) {
     UserManager::Show(base::FilePath(),
                       profiles::USER_MANAGER_NO_TUTORIAL,
                       profiles::USER_MANAGER_SELECT_PROFILE_NO_ACTION);
   } else {
     CreateBrowser(lastProfile);
   }
 
   // We've handled the reopen event, so return NO to tell AppKit not
   // to do anything.
   return NO;
@@ skipping 440 matching lines @@
 
 //---------------------------------------------------------------------------
 
 namespace app_controller_mac {
 
 bool IsOpeningNewWindow() {
   return g_is_opening_new_window;
 }
 
 }  // namespace app_controller_mac