Avoid two targeting phases in aura client-lib and EventProcessor.

ui/aura/mus/window_tree_client.cc

Index: ui/aura/mus/window_tree_client.cc
diff --git a/ui/aura/mus/window_tree_client.cc b/ui/aura/mus/window_tree_client.cc
index b71391bc5bab8f5977235c55f7e570fe3f791b1c..7bc6ecccd7b5305f8c91bf4df877786ed24333ff 100644
--- a/ui/aura/mus/window_tree_client.cc
+++ b/ui/aura/mus/window_tree_client.cc
@@ -1149,30 +1149,32 @@ void WindowTreeClient::OnWindowInputEvent(uint32_t event_id,
   WindowTreeHostMus* host = GetWindowTreeHostMus(window);
   DCHECK(host);
 
-  // The location of the event is relative to |window|. As the event is handed
-  // to WindowTreeHost we need it to be relative to WindowTreeHost.
-  if (event->IsLocatedEvent()) {
-    gfx::Point host_location = event->AsLocatedEvent()->location();
-    aura::Window::ConvertPointToTarget(window->GetWindow(), host->window(),
-                                       &host_location);
-    event->AsLocatedEvent()->set_location(host_location);
-  }
-
   EventAckHandler ack_handler(CreateEventResultCallback(event_id));
   // TODO(moshayedi): crbug.com/617222. No need to convert to ui::MouseEvent or
   // ui::TouchEvent once we have proper support for pointer events.
   if (event->IsMousePointerEvent()) {
     if (event->type() == ui::ET_POINTER_WHEEL_CHANGED) {
       ui::MouseWheelEvent mapped_event(*event->AsPointerEvent());
+      // Set the target window of this event to be the window received from mus
+      // window server. EventProcessor will use this target window for event
+      // dispatching instead of trying to find the right target window again.
+      ui::Event::DispatcherApi dispatch_helper(&mapped_event);
+      dispatch_helper.set_target(window->GetWindow());
       host->SendEventToProcessor(&mapped_event);
     } else {
       ui::MouseEvent mapped_event(*event->AsPointerEvent());
+      ui::Event::DispatcherApi dispatch_helper(&mapped_event);
+      dispatch_helper.set_target(window->GetWindow());
       host->SendEventToProcessor(&mapped_event);
     }
   } else if (event->IsTouchPointerEvent()) {
     ui::TouchEvent mapped_event(*event->AsPointerEvent());
+    ui::Event::DispatcherApi dispatch_helper(&mapped_event);
+    dispatch_helper.set_target(window->GetWindow());
     host->SendEventToProcessor(&mapped_event);
   } else {
+    ui::Event::DispatcherApi dispatch_helper(event.get());
+    dispatch_helper.set_target(window->GetWindow());
     host->SendEventToProcessor(event.get());

[sadrul, 2017/02/08 00:24:38]

This should go into some helper function, e.g.
WindowTreeClient::DispatchEventToTarget(ui::Event* event, Window* target);

[riajiang, 2017/02/11 00:43:39]

Done.

   }
   ack_handler.set_handled(event->handled());