[SystemInfo API] Rewrite DisplayInfoProvider without SystemInfoProvider.

Since many UI operations are done on UI thread, there is no need to
create a SequenceWorkerPool and tasks for display API.

BUG=122863
TEST=browser_test --gtest_filter=SystemDisplayApiTest.*

Review URL: https://codereview.chromium.org/23441032

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226102 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 226102