Initial commit of Suggestions service.

BUG=None
Test=SuggestionsServiceTest

Review URL: https://codereview.chromium.org/142193007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@249862 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 249862