Add GN function get_label_info

tools/gn/filesystem_utils_unittest.cc

Index: tools/gn/filesystem_utils_unittest.cc
diff --git a/tools/gn/filesystem_utils_unittest.cc b/tools/gn/filesystem_utils_unittest.cc
index ec1a53e7633d04d11d67f9c662a403af830dadac..906d672bdd2db245de6e21eca04be4b3e9eaa0fa 100644
--- a/tools/gn/filesystem_utils_unittest.cc
+++ b/tools/gn/filesystem_utils_unittest.cc
@@ -336,7 +336,7 @@ TEST(FilesystemUtils, GetToolchainDirs) {
   EXPECT_EQ("//out/Debug/gen/",
             GetToolchainGenDir(&default_settings).value());
 
-  Settings other_settings(&build_settings, "two");
+  Settings other_settings(&build_settings, "two/");
   EXPECT_EQ("//out/Debug/two/",
             GetToolchainOutputDir(&other_settings).value());
   EXPECT_EQ("//out/Debug/two/gen/",
@@ -357,7 +357,7 @@ TEST(FilesystemUtils, GetOutDirForSourceDir) {
                                      SourceDir("//foo/bar/")).value());
 
   // Secondary toolchain.
-  Settings other_settings(&build_settings, "two");
+  Settings other_settings(&build_settings, "two/");
   EXPECT_EQ("//out/Debug/two/obj/",
             GetOutputDirForSourceDir(&other_settings, SourceDir("//")).value());
   EXPECT_EQ("//out/Debug/two/obj/foo/bar/",
@@ -378,7 +378,7 @@ TEST(FilesystemUtils, GetGenDirForSourceDir) {
                                   SourceDir("//foo/bar/")).value());
 
   // Secondary toolchain.
-  Settings other_settings(&build_settings, "two");
+  Settings other_settings(&build_settings, "two/");
   EXPECT_EQ("//out/Debug/two/gen/",
             GetGenDirForSourceDir(&other_settings, SourceDir("//")).value());
   EXPECT_EQ("//out/Debug/two/gen/foo/bar/",