mash: Use the new mus drag and drop API to get drag working in mash.

services/ui/ws/window_manager_state.cc

Index: services/ui/ws/window_manager_state.cc
diff --git a/services/ui/ws/window_manager_state.cc b/services/ui/ws/window_manager_state.cc
index 93b3d3cde76d15cbce86a6f860f7faea12770a9f..04756f191bf6da135bd54e08ec2f03c372c99ab4 100644
--- a/services/ui/ws/window_manager_state.cc
+++ b/services/ui/ws/window_manager_state.cc
@@ -162,9 +162,17 @@ void WindowManagerState::SetDragDropSourceWindow(
     DragSource* drag_source,
     ServerWindow* window,
     DragTargetConnection* source_connection,
-    int32_t drag_pointer,
     mojo::Map<mojo::String, mojo::Array<uint8_t>> drag_data,
     uint32_t drag_operation) {
+  int32_t drag_pointer = PointerEvent::kMousePointerId;
+  if (event_awaiting_input_ack_ &&
+      event_awaiting_input_ack_->AsPointerEvent()) {
+    drag_pointer = event_awaiting_input_ack_->AsPointerEvent()->pointer_id();

[Elliot Glaysher, 2016/09/26 20:57:29]

In the server, do I have to handle things other than pointer events here? There
are no GestureEvents in the ws/ directory and the one place in
platform_display.cc which translates MouseEvents and TouchEvents to
PointerEvents.

[sky, 2016/09/26 21:44:41]

You should at least check that event_awaiting_input_ack_ is a pointer event
(IsPointerEvent()).
Once 571688 then gestures will be possible.

[Elliot Glaysher, 2016/09/26 22:20:02]

Misunderstood interface; thought it returned null if AsPointer() would fail.

+  } else {
+    NOTIMPLEMENTED() << "Set drag drop set up during something other than a "

[sky, 2016/09/26 21:44:41]

Can the NOTIMPLEMENTED case fail? I'm ok if you want to fix up separately.

[Elliot Glaysher, 2016/09/26 22:20:02]

Done.

+                     << "pointer event; defaulting to mouse pointer.";
+  }
+
   event_dispatcher_.SetDragDropSourceWindow(
       drag_source, window, source_connection, drag_pointer,
       std::move(drag_data), drag_operation);
@@ -415,10 +423,10 @@ void WindowManagerState::DispatchInputEventToWindowImpl(
   DCHECK(tree);
   ScheduleInputEventTimeout(tree);
 
-  if (accelerator) {
-    event_awaiting_input_ack_ = ui::Event::Clone(event);

[sky, 2016/09/26 21:44:41]

Why do you need to do this change?

[Elliot Glaysher, 2016/09/26 22:20:02]

Because we need to keep track of the event awaiting input, and this isn't doing
that.

In this previous code, we're only keeping track of the event which triggered an
input if we had an accelerator associated with the action; accelerator can be
null any other time. (ie DispatchInputEventToWindow()).

This change actually brings the code into line with the comment on
event_awaiting_input_ack_ in the header.

[sky, 2016/09/26 23:06:05]

Got it.

+  event_awaiting_input_ack_ = ui::Event::Clone(event);
+
+  if (accelerator)
     post_target_accelerator_ = accelerator;
-  }
 
   // Ignore |tree| because it will receive the event via normal dispatch.
   window_server()->SendToPointerWatchers(event, user_id(), target, tree);