clang/win: Let some chromium_code targets build with -Wextra.

sandbox/win/src/sandbox_policy_base.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/sandbox_policy_base.h"
 
 #include <sddl.h>
 
 #include "base/basictypes.h"
 #include "base/callback.h"
@@ skipping 617 matching lines @@
   return SBOX_ALL_OK;
 }
 
 const AppContainerAttributes* PolicyBase::GetAppContainer() const {
   if (!appcontainer_list_.get() || !appcontainer_list_->HasAppContainer())
     return NULL;
 
   return appcontainer_list_.get();
 }
 
-const PSID PolicyBase::GetLowBoxSid() const {
+PSID PolicyBase::GetLowBoxSid() const {
   return lowbox_sid_;
 }
 
 bool PolicyBase::AddTarget(TargetProcess* target) {
   if (NULL != policy_)
     policy_maker_->Done();
 
   if (!ApplyProcessMitigationsToSuspendedProcess(target->Process(),
                                                  mitigations_)) {
     return false;
@@ skipping 225 matching lines @@
       break;
     }
 
     default: { return SBOX_ERROR_UNSUPPORTED; }
   }
 
   return SBOX_ALL_OK;
 }
 
 }  // namespace sandbox