Fully support the autohide shelf option for touch UI on Windows.

ui/aura/test/event_generator.cc

Index: ui/aura/test/event_generator.cc
diff --git a/ui/aura/test/event_generator.cc b/ui/aura/test/event_generator.cc
index e914a77a72547b08132422f8066c827bd1cecd6c..d3c6d7fafceb85b4d048a830864be90ff3290b37 100644
--- a/ui/aura/test/event_generator.cc
+++ b/ui/aura/test/event_generator.cc
@@ -248,6 +248,18 @@ void EventGenerator::PressMoveAndReleaseTouchToCenterOf(Window* window) {
   PressMoveAndReleaseTouchTo(CenterOfWindow(window));
 }
 
+void EventGenerator::GestureEdgeSwipe() {
+  ui::GestureEvent gesture(
+      ui::ET_GESTURE_WIN8_EDGE_SWIPE,
+      0,
+      0,
+      0,
+      ui::EventTimeForNow(),
+      ui::GestureEventDetails(ui::ET_GESTURE_WIN8_EDGE_SWIPE, 0, 0),
+      0);
+  Dispatch(&gesture);
+}
+
 void EventGenerator::GestureTapAt(const gfx::Point& location) {
   const int kTouchId = 2;
   ui::TouchEvent press(ui::ET_TOUCH_PRESSED,