[Most Visited] Log suggestion provider to UMA

Will add a query param to the /log.html endpoint in order to be able to log the suggestion provider to UMA.

BUG=None
TEST=MostVisitedIframeSourceTest
NOTRY=true

Review URL: https://codereview.chromium.org/111423005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@241064 0039d316-1c4b-4281-b951-d872f2087c98
Allow the max url length to be overridden

This is needed for WebView Classic compatibility, and since it shipped with KK it is needed to finish unforking.

There is no define to separate between Android WebView and
Chrome for Android which is why this is done with a setter
function instead of a define.

NOTRY=true
BUG=298495

Review URL: https://codereview.chromium.org/112053002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@241065 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 241065