Remove RenderProcessHost notifications from search_provider_install_*.

BUG=170921
TEST=everything still works

Review URL: https://codereview.chromium.org/107543006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@246358 0039d316-1c4b-4281-b951-d872f2087c98
Record stats whether a prerender has been visited before, based on the
history database.

R=asvitkine@chromium.org, davidben@chromium.org

Review URL: https://codereview.chromium.org/145043002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@246359 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 246359