Use CategoryFilter::kDefaultCategoryFilterString instead of "*" as the default category

NOTRY=true (passed presubmit and android try bots)
R=skyostil@chromium.org, yfriedman@chromium.org

Review URL: https://codereview.chromium.org/26358012

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@229195 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 229195