Revert changes to have ExtensionService notify ThemeService directly for themes

Changes r170880 introduced a regression and r171368 only partially fixed it.

Reverting both of them to get back to a clean state.

BUG=164400
TBR=asargent@chromium.org,pkotwicz@chromium.org,erg@chromium.org

Review URL: https://codereview.chromium.org/11445038

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@171391 0039d316-1c4b-4281-b951-d872f2087c98
7 files changed