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

ash/wm/gestures/shelf_gesture_handler.cc

Index: ash/wm/gestures/shelf_gesture_handler.cc
diff --git a/ash/wm/gestures/shelf_gesture_handler.cc b/ash/wm/gestures/shelf_gesture_handler.cc
index f9fb1b8d43c250f6e8575fa4ddf090e7485a0c69..9a0de983417148af3c3d9f0334a604f59362eb2b 100644
--- a/ash/wm/gestures/shelf_gesture_handler.cc
+++ b/ash/wm/gestures/shelf_gesture_handler.cc
@@ -43,6 +43,13 @@ bool ShelfGestureHandler::ProcessGestureEvent(const ui::GestureEvent& event) {
 
   ShelfLayoutManager* shelf = controller->GetShelfLayoutManager();
 
+#if defined(OS_WIN)

[sky, 2014/02/11 18:55:22]

Is there a reason we need the ifdefs here and in the test? The events won't be
generated other than win8, but it should be fine to test, right?

+  if (event.type() == ui::ET_GESTURE_WIN8_EDGE_SWIPE) {
+    shelf->OnGestureEdgeSwipe(event);
+    return true;
+  }
+#endif
+
   const aura::Window* fullscreen = controller->GetWindowForFullscreenMode();
   if (fullscreen &&
       ash::wm::GetWindowState(fullscreen)->hide_shelf_when_fullscreen()) {