Temporarily disable Publishing of SiteDetails to UMA.

https://codereview.chromium.org/23841002/ temporariliy breaks frame tree
accounting logic for tip of tree. Disable this UMA stat until frame
tree accounting is fixed to avoid polluting the data.

BUG=245126
R=creis@chromium.org, thakis@chromium.org

Review URL: https://codereview.chromium.org/24980004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@225815 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 225815