Close omnibox popup when user drags the location URL icon or text in the omnibox.  The user may have wanted to drag it to something is was covered by the omnibox popup.

BUG=356887

Review URL: https://codereview.chromium.org/251373004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@269402 0039d316-1c4b-4281-b951-d872f2087c98

• chrome/browser/autocomplete/autocomplete_controller.h[diff]
• chrome/browser/ui/views/location_bar/location_icon_view.cc[diff]
• chrome/browser/ui/views/location_bar/location_icon_view.h[diff]
• chrome/browser/ui/views/omnibox/omnibox_view_views.cc[diff]
• chrome/browser/ui/views/omnibox/omnibox_view_views.h[diff]
• chrome/browser/ui/views/omnibox/omnibox_view_views_browsertest.cc[diff]