Revert changes to have ExtensionService notify ThemeService directly

This reverts r159875 and r170640.  It cause a performance regression
that's not easy to fix, as detailed in the bug.

BUG=163706
[email protected],[email protected],[email protected]

Review URL: https://codereview.chromium.org/11416324

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@170824 0039d316-1c4b-4281-b951-d872f2087c98
9 files changed