[chromium] Add tools/protoc_wrapper to directories pulled in Chromium-in-WebKit configuration
https://bugs.webkit.org/show_bug.cgi?id=112363

Patch by James Robinson <jamesr@chromium.org> on 2013-03-14
Reviewed by Kenneth Russell.

Chromium r187704 added a reference to this script to src/gpu/gpu.gyp, which we pull in the Chromium-in-WebKit
configuration. This adds the script to DEPS so we can roll past that rev.

* DEPS:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@145829 268f45cc-cd09-0410-ab3c-d52691b4dbfc