Allow the MITIGATION_WIN32K_DISABLE process mitigation to be set in the renderer sandbox.

sandbox/win/src/process_mitigations.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 "sandbox/win/src/process_mitigations.h"
 
 #include <algorithm>
 
 #include "base/win/windows_version.h"
 #include "sandbox/win/src/nt_internals.h"
@@ skipping 290 matching lines @@
 
 bool CanSetProcessMitigationsPostStartup(MitigationFlags flags) {
   // All of these mitigations can be enabled after startup.
   return !(flags & ~(MITIGATION_HEAP_TERMINATE |
                      MITIGATION_DEP |
                      MITIGATION_DEP_NO_ATL_THUNK |
                      MITIGATION_RELOCATE_IMAGE |
                      MITIGATION_RELOCATE_IMAGE_REQUIRED |
                      MITIGATION_BOTTOM_UP_ASLR |
                      MITIGATION_STRICT_HANDLE_CHECKS |
-                     MITIGATION_WIN32K_DISABLE |
                      MITIGATION_EXTENSION_DLL_DISABLE |
                      MITIGATION_DLL_SEARCH_ORDER));
 }
 
 bool CanSetProcessMitigationsPreStartup(MitigationFlags flags) {
   // These mitigations cannot be enabled prior to startup.
   return !(flags & (MITIGATION_STRICT_HANDLE_CHECKS |
-                    MITIGATION_WIN32K_DISABLE |
                     MITIGATION_DLL_SEARCH_ORDER));
 }
 
 }  // namespace sandbox