Moved PrerenderManager to ProfileKeyedService system.

As per https://groups.google.com/a/chromium.org/group/chromium-dev/browse_thread/thread/554b5b0ca05e001d# it is recommended that weak references to services be removed from Profiles and constructed as ProfileKeyedServices instead. This does this for the PrerenderManager.

(Continuation of http://codereview.chromium.org/7795009/)

BUG=94643
TEST=Prerender*


Review URL: http://codereview.chromium.org/7846001

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@104130 0039d316-1c4b-4281-b951-d872f2087c98
24 files changed