Fix typo inside comment in base/bind_helpers.h.

BUG=

Review URL: https://codereview.chromium.org/259523004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@266278 0039d316-1c4b-4281-b951-d872f2087c98
1 file changed