GN: toolchain threading cleanup

tools/gn/ninja_helper.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_NINJA_HELPER_H_
 #define TOOLS_GN_NINJA_HELPER_H_
 
 #include <iosfwd>
 #include <string>
 
@@ skipping 34 matching lines @@
 
   // Returns the filename produced by the given output.
   //
   // Some targets make multiple files (like a .dll and an import library). This
   // function returns the name of the file other targets should depend on and
   // link to (so in this example, the import library).
   OutputFile GetTargetOutputFile(const Target* target) const;
 
   // Returns the prefix for rules on the given toolchain. We need this to
   // disambiguate a given rule for each toolchain.
-  std::string GetRulePrefix(const Toolchain* toolchain) const;
+  std::string GetRulePrefix(const Settings* settings) const;
 
   // Returns the name of the rule name for the given toolchain and file/target
   // type.  Returns the empty string for source files with no command.
   std::string GetRuleForSourceType(const Settings* settings,
-                                   const Toolchain* toolchain,
                                    SourceFileType type) const;
 
   // Returns the relative directory in either slashes or the system separator
   // from the ninja directory (e.g. "out/Debug") to the source root (e.g.
   // "../.."). It has no terminating slash.
   const std::string& build_to_src_no_last_slash() const {
     return build_to_src_no_last_slash_;
   }
   const std::string& build_to_src_system_no_last_slash() const {
     return build_to_src_system_no_last_slash_;
   }
 
  private:
   const BuildSettings* build_settings_;
 
   std::string build_to_src_no_last_slash_;
   std::string build_to_src_system_no_last_slash_;
 
   DISALLOW_COPY_AND_ASSIGN(NinjaHelper);
 };
 
 #endif  // TOOLS_GN_NINJA_HELPER_H_