Remove dependency of ExtensionService on runtime API.

TBR=derat
BUG=298537

Review URL: https://codereview.chromium.org/93473002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@237880 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 237880