[Android] Out with the Android GR, in with the new unified C++ GR

Wire up the new gesture detection code from ui/events/gesture_detection in
ContentViewCoreImpl. Also remove the old gesture detection code in
ContentViewGestureHandler and SnapScrollController.

BUG=332418,320428,341613

Review URL: https://codereview.chromium.org/181833003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@254356 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 254356