This check is specific to Chromium codebase, there's no point in having it in depot_tools.

BUG=None
R=maruel@chromium.org

Review URL: https://codereview.chromium.org/924863002

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@294124 0039d316-1c4b-4281-b951-d872f2087c98