Add back helper method still used in build repo

Follow up fix for:
https://chromium-review.googlesource.com/c/497432

TBR=tandrii@chromium.org

Bug: 717457
Change-Id: I66fb86f46cbdc6d9e34ce656541760af313beea8
Reviewed-on: https://chromium-review.googlesource.com/497410Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>

recipes/recipe_modules/gclient/config.py

@@ -102,6 +102,10 @@ config_ctx = config_item_context(BaseConfig)
 def ChromiumGitURL(_c, *pieces):
   return '/'.join(('https://chromium.googlesource.com',) + pieces)
 
+# TODO(phajdan.jr): Move to proper repo and add coverage.
+def ChromeInternalGitURL(_c, *pieces):  # pragma: no cover
+  return '/'.join(('https://chrome-internal.googlesource.com',) + pieces)
+
 @config_ctx()
 def android(c):
   c.target_os.add('android')