Add Get/SetMetaInfo methods to BookmarkManagerPrivate Api

Adds access to the meta info bookmark field in order to fascilitate
experimenting with the bookmark manager.

BUG=312488

Review URL: https://codereview.chromium.org/54213005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@233126 0039d316-1c4b-4281-b951-d872f2087c98
Convert event location to screen position.

BUG=313859
TEST=OverviewGestureHandlerTest.GestureSwipeTopOfWindow
TEST=Swipe down from the top of a window not at the top of the screen. Overview should not engage.

Review URL: https://codereview.chromium.org/54333008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@233127 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 233127