exo: Replace fling cancel with generic zero distance scroll

components/exo/pointer.cc

Index: components/exo/pointer.cc
diff --git a/components/exo/pointer.cc b/components/exo/pointer.cc
index e650b4f4ffe35b7732e406cdf59a315515d966a9..ae53458ff93b258cba5c1ea7ed98092437e61938 100644
--- a/components/exo/pointer.cc
+++ b/components/exo/pointer.cc
@@ -212,8 +212,13 @@ void Pointer::OnMouseEvent(ui::MouseEvent* event) {
       break;
     }
     case ui::ET_SCROLL_FLING_CANCEL: {
-      delegate_->OnPointerScrollCancel(event->time_stamp());
-      delegate_->OnPointerFrame();
+      if (last_event_type_ == ui::ET_SCROLL_FLING_START) {

[reveman, 2017/04/27 13:28:17]

Can you add a comment here that explains why we do this?

[denniskempin (chromium), 2017/05/03 20:55:28]

Done.

+        delegate_->OnPointerScroll(event->time_stamp(), gfx::Vector2dF(),

[reveman, 2017/04/27 13:28:17]

I think this logic deserves a comment similar to what we had in server.cc

[denniskempin (chromium), 2017/05/03 20:55:28]

Done.

+                                   false);
+        delegate_->OnPointerFrame();
+        delegate_->OnPointerScrollStop(event->time_stamp());
+        delegate_->OnPointerFrame();
+      }
       break;
     }
     case ui::ET_MOUSE_MOVED:
@@ -227,6 +232,7 @@ void Pointer::OnMouseEvent(ui::MouseEvent* event) {
       break;
   }
 
+  last_event_type_ = event->type();
   UpdateCursorScale();
 }