Setting "SubSystem" option on "Link" page for Visual Studio project.

tools/gn/visual_studio_utils_unittest.cc

Index: tools/gn/visual_studio_utils_unittest.cc
diff --git a/tools/gn/visual_studio_utils_unittest.cc b/tools/gn/visual_studio_utils_unittest.cc
index c4e253054524dd562231c316187ab3b856c93ed5..261c030536da1cfad5cf21423a47ffeba3cb1f78 100644
--- a/tools/gn/visual_studio_utils_unittest.cc
+++ b/tools/gn/visual_studio_utils_unittest.cc
@@ -92,3 +92,12 @@ TEST(VisualStudioUtils, ParseCompilerOption) {
   ParseCompilerOption("/Zc:sizedDealloc", &options);
   ASSERT_EQ("/MP /bigobj /Zc:sizedDealloc ", options.additional_options);
 }
+
+TEST(VisualStudioUtils, ParseLinkerOption) {
+  LinkerOptions options;
+  ParseLinkerOption("/SUBSYSTEM:CONSOLE,5.02h", &options);
+  ASSERT_EQ("CONSOLE", options.subsystem);
+
+  ParseLinkerOption("/SUBSYSTEM:WINDOWS", &options);
+  ASSERT_EQ("WINDOWS", options.subsystem);
+}