Add presubmit check for bad anonymous variables

These types are all scoped locks and should never be in an anonymous
variable.  A presubmit check is not watertight, but should go a long way
towards avoiding this class of bugs.

I ran this check over Chromium and there were no false positives in the
codebase.

This CL is meant as an alternative to the macro and extra parentheses
approach described in https://codereview.chromium.org/71713004/

BUG=none

Review URL: https://codereview.chromium.org/100743004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@238618 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 238618