Add DOM distiller service

This adds the core DomDistillerService, a wrapped version of that
making it a BrowserContextKeyedService, and the corresponding
BrowserContextKeyedServiceFactory.

Currently, the service has an interface but doesn't actually implement
any of the methods.

This also adds some interfaces to the distiller that the service 
depends on. These also have no implementation.

BUG=288015

Review URL: https://codereview.chromium.org/26338002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@228078 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 228078
Revert 221394 "Remove IBus specific hack from InputMethodIBus."

> Remove IBus specific hack from InputMethodIBus.
> 
> BUG=None
> TEST=None, just working fine.
> 
> Review URL: https://chromiumcodereview.appspot.com/22909048

TBR=nona@chromium.org

Review URL: https://codereview.chromium.org/26262003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@228079 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 228079