Merge to XFA: Update link to chromium src.

This CL updates the documentation link to the Chromium PDF plugin to
point to Gitiles instead of the SVN repo.

Merge clean.

TBR=tsepez@chromium.org

Review URL: https://codereview.chromium.org/1407313002 .

(cherry picked from commit 8969a70de3ed74bf0e2ae133378f5e7a4d1fd4c0)

Review URL: https://codereview.chromium.org/1412723002 .
1 file changed