Apply the pref that prohibits deleting browsing and download history.
When kDeletingBrowserHistoryEnabled is false, the UI elements to delete history items will be disabled, and the back-end calls will likewise be skipped (in case someone works around the UI, e.g. via the JavaScript console).
BUG=230401
TEST=browser_tests --gtest_filter=HistoryWebUIDeleteProhibitedTest.*
Review URL: https://chromiumcodereview.appspot.com/
14046016
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@196655 0039d316-1c4b-4281-b951-d872f2087c98