Add code to keep track of what fraction of pageviews are top sites.

Add code to keep track of what fraction of pageviews are top sites.
This code will be removed again once histograms have been collected (prior
to the M15 branchpoint).
R=cbentzel@chromium.org, dominich@chromium.org
Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=98250

[tburkard, 2011-08-24 23:21:48]

Ok trying this again hopefully this will not break the build this time :)

The only change was adding GetTopSites(), and to verify that profile_ != NULL.

I will run the unit test locally and wait for the result of the try run to
verify before I commit.

[dominich, 2011-08-24 23:37:20]

LGTM++

again ;)

http://codereview.chromium.org/7741002/diff/1/chrome/browser/prerender/preren...
File chrome/browser/prerender/prerender_manager.cc (right):

http://codereview.chromium.org/7741002/diff/1/chrome/browser/prerender/preren...
chrome/browser/prerender/prerender_manager.cc:215: history::TopSites*
GetTopSites() const {
nit: is it worth caching the TopSites pointer instead of the Profile pointer?