Remove obsolete OS handling in GN.

tools/gn/settings.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_SETTINGS_H_
 #define TOOLS_GN_SETTINGS_H_
 
 #include "base/files/file_path.h"
 #include "tools/gn/build_settings.h"
 #include "tools/gn/import_manager.h"
 #include "tools/gn/output_file.h"
 #include "tools/gn/scope.h"
 #include "tools/gn/source_dir.h"
 #include "tools/gn/toolchain.h"
 
 // Holds the settings for one toolchain invocation. There will be one
 // Settings object for each toolchain type, each referring to the same
 // BuildSettings object for shared stuff.
 //
 // The Settings object is const once it is constructed, which allows us to
 // use it from multiple threads during target generation without locking (which
 // is important, because it gets used a lot).
 //
 // The Toolchain object holds the set of stuff that is set by the toolchain
 // declaration, which obviously needs to be set later when we actually parse
 // the file with the toolchain declaration in it.
 class Settings {
  public:
-  enum TargetOS {
-    UNKNOWN,
-    LINUX,
-    MAC,
-    WIN
-  };
-
   // Constructs a toolchain settings.
   //
   // The output_subdir_name is the name we should use for the subdirectory in
   // the build output directory for this toolchain's outputs. The default
   // toolchain would use an empty string (it goes in the root build dir).
   // Otherwise, it must end in a slash.
   Settings(const BuildSettings* build_settings,
            const std::string& output_subdir_name);
   ~Settings();
 
   const BuildSettings* build_settings() const { return build_settings_; }
 
   const Label& toolchain_label() const { return toolchain_label_; }
   void set_toolchain_label(const Label& l) { toolchain_label_ = l; }
 
   const Label& default_toolchain_label() const {
     return default_toolchain_label_;
   }
   void set_default_toolchain_label(const Label& default_label) {
     default_toolchain_label_ = default_label;
   }
 
   // Indicates if this corresponds to the default toolchain.
   bool is_default() const {
     return toolchain_label_ == default_toolchain_label_;
   }
 
-  bool IsMac() const { return target_os_ == MAC; }
-  bool IsLinux() const { return target_os_ == LINUX; }
-  bool IsWin() const { return target_os_ == WIN; }
-
-  TargetOS target_os() const { return target_os_; }
-  void set_target_os(TargetOS t) { target_os_ = t; }
-
   const OutputFile& toolchain_output_subdir() const {
     return toolchain_output_subdir_;
   }
   const SourceDir& toolchain_output_dir() const {
     return toolchain_output_dir_;
   }
 
   // Directory for generated files.
   const SourceDir& toolchain_gen_dir() const {
     return toolchain_gen_dir_;
@@ skipping 19 matching lines @@
   void set_greedy_target_generation(bool gtg) {
     greedy_target_generation_ = gtg;
   }
 
  private:
   const BuildSettings* build_settings_;
 
   Label toolchain_label_;
   Label default_toolchain_label_;
 
-  TargetOS target_os_;
-
   mutable ImportManager import_manager_;
 
   // The subdirectory inside the build output for this toolchain. For the
   // default toolchain, this will be empty (since the deafult toolchain's
   // output directory is the same as the build directory). When nonempty, this
   // is guaranteed to end in a slash.
   OutputFile toolchain_output_subdir_;
 
   // Full source file path to the toolchain output directory.
   SourceDir toolchain_output_dir_;
 
   SourceDir toolchain_gen_dir_;
 
   Scope base_config_;
 
   bool greedy_target_generation_;
 
   DISALLOW_COPY_AND_ASSIGN(Settings);
 };
 
 #endif  // TOOLS_GN_SETTINGS_H_