Make some global pointers const void* const.

tools/gn/loader.h

 // Copyright (c) 2013 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 TOOLS_GN_LOADER_H_
 #define TOOLS_GN_LOADER_H_
 
 #include <map>
 #include <set>
 
@@ skipping 45 matching lines @@
   // label, and calls Load().
   void Load(const Label& label, const LocationRange& origin);
 
   // Returns the build file that the given label references.
   static SourceFile BuildFileForLabel(const Label& label);
 
   // When processing the default build config, we want to capture the argument
   // of set_default_build_config. The implementation of that function uses this
   // constant as a property key to get the Label* out of the scope where the
   // label should be stored.
-  static const void* kDefaultToolchainKey;
+  static const void* const kDefaultToolchainKey;
 
  protected:
   friend class base::RefCountedThreadSafe<Loader>;
   virtual ~Loader();
 };
 
 class LoaderImpl : public Loader {
  public:
   // Callback to emulate InputFileManager::AsyncLoadFile.
   typedef base::Callback<bool(const LocationRange&,
@@ skipping 95 matching lines @@
   const BuildSettings* build_settings_;
   Label default_toolchain_label_;
 
   // Records for the build config file loads.
   // Owning pointers.
   typedef std::map<Label, ToolchainRecord*> ToolchainRecordMap;
   ToolchainRecordMap toolchain_records_;
 };
 
 #endif  // TOOLS_GN_LOADER_H_