This CL does this for content area context menus only. I will send out another CL for same functionality on views controls.
We acheive this as follows: We remember in render_widget_host, which kind of
event is currently in process. When we get a request for showing context menu,
in render_view_host, we check if currently we are processing a gesture event,
and if so, we display the context menu appropriately.
BUG=142015
TEST=manual
Review URL: https://chromiumcodereview.appspot.com/10917102
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@155306 0039d316-1c4b-4281-b951-d872f2087c98