Windows precompiled header support in GN

tools/gn/config_values.h

Index: tools/gn/config_values.h
diff --git a/tools/gn/config_values.h b/tools/gn/config_values.h
index dec43c691a3e18a3aaac8ed40cdb5c5b04d0e021..64c0acc5922335664a559a6766536e4de10b43b8 100644
--- a/tools/gn/config_values.h
+++ b/tools/gn/config_values.h
@@ -10,6 +10,7 @@
 
 #include "base/basictypes.h"
 #include "tools/gn/source_dir.h"
+#include "tools/gn/source_file.h"
 
 // Holds the values (include_dirs, defines, compiler flags, etc.) for a given
 // config or target.
@@ -39,6 +40,22 @@ class ConfigValues {
 #undef STRING_VALUES_ACCESSOR
 #undef DIR_VALUES_ACCESSOR
 
+  bool has_precompiled_headers() const {
+    return !precompiled_header_.empty() || !precompiled_source_.is_null();
+  }
+  const std::string& precompiled_header() const {
+    return precompiled_header_;
+  }
+  void set_precompiled_header(const std::string& f) {
+    precompiled_header_ = f;
+  }
+  const SourceFile& precompiled_source() const {
+    return precompiled_source_;
+  }
+  void set_precompiled_source(const SourceFile& f) {
+    precompiled_source_ = f;
+  }
+
  private:
   std::vector<std::string> cflags_;
   std::vector<std::string> cflags_c_;
@@ -51,6 +68,8 @@ class ConfigValues {
   std::vector<SourceDir>   lib_dirs_;
   std::vector<std::string> libs_;
 
+  std::string precompiled_header_;
+  SourceFile precompiled_source_;
 
   DISALLOW_COPY_AND_ASSIGN(ConfigValues);
 };