Implement top controls show/hide functionality for main thread scrolling

Source/web/PageWidgetDelegate.cpp

Index: Source/web/PageWidgetDelegate.cpp
diff --git a/Source/web/PageWidgetDelegate.cpp b/Source/web/PageWidgetDelegate.cpp
index 72341ae700d6de189ef837d60138eaab10b6b086..bd1c02af4f4383884bbf7cf4e2a5d4dda82dbd68 100644
--- a/Source/web/PageWidgetDelegate.cpp
+++ b/Source/web/PageWidgetDelegate.cpp
@@ -174,15 +174,12 @@ bool PageWidgetDelegate::handleInputEvent(PageWidgetEventHandler& handler, const
         if (!root || !root->view())
             return false;
         return handler.handleTouchEvent(*root, static_cast<const WebTouchEvent&>(event));
-
     case WebInputEvent::GesturePinchBegin:
     case WebInputEvent::GesturePinchEnd:
     case WebInputEvent::GesturePinchUpdate:
-        // FIXME: Once PlatformGestureEvent is updated to support pinch, this
-        // should call handleGestureEvent, just like it currently does for
-        // gesture scroll.
+        // Touchscreen pinch events are currently not handled in main thread. Once they are,
+        // these should be passed to |handleGestureEvent| similar to gesture scroll events.
         return false;
-
     default:
         return false;
     }