Fix illegal use of const in container contents to unbreak VS 2015.

sandbox/win/src/handle_closer.h

 // 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.
 
 #ifndef SANDBOX_SRC_HANDLE_CLOSER_H_
 #define SANDBOX_SRC_HANDLE_CLOSER_H_
 
 #include <map>
 #include <set>
 
 #include "base/basictypes.h"
 #include "base/strings/string16.h"
 #include "sandbox/win/src/interception.h"
 #include "sandbox/win/src/sandbox_types.h"
 #include "sandbox/win/src/target_process.h"
 
 namespace sandbox {
 
 // This is a map of handle-types to names that we need to close in the
 // target process. A null set means we need to close all handles of the
 // given type.
-typedef std::map<const base::string16, std::set<const base::string16> >
-    HandleMap;
+typedef std::map<const base::string16, std::set<base::string16> > HandleMap;
 
 // Type and set of corresponding handle names to close.
 struct HandleListEntry {
   size_t record_bytes;       // Rounded to sizeof(size_t) bytes.
   size_t offset_to_names;    // Nul terminated strings of name_count names.
   size_t name_count;
   base::char16 handle_type[1];
 };
 
 // Global parameters and a pointer to the list of entries.
@@ skipping 31 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(HandleCloser);
 };
 
 // Returns the object manager's name associated with a handle
 bool GetHandleName(HANDLE handle, base::string16* handle_name);
 
 }  // namespace sandbox
 
 #endif  // SANDBOX_SRC_HANDLE_CLOSER_H_