Fix typo in GN get_label_info help

BUG=None

Review URL: https://codereview.chromium.org/1459733004

Cr-Original-Commit-Position: refs/heads/master@{#360924}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: de3c7279759c9bf318961371c5454eeecac508a3
diff --git a/tools/gn/function_get_label_info.cc b/tools/gn/function_get_label_info.cc
index dd5e586..be22cca 100644
--- a/tools/gn/function_get_label_info.cc
+++ b/tools/gn/function_get_label_info.cc
@@ -63,7 +63,7 @@
     "\n"
     "  \"root_out_dir\"\n"
     "      The root of the output file tree for the target. This will\n"
-    "      match the value of the \"root_gen_dir\" variable when inside that\n"
+    "      match the value of the \"root_out_dir\" variable when inside that\n"
     "      target's declaration.\n"
     "\n"
     "  \"label_no_toolchain\"\n"