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..71932238bd08517bdb16a95e2deaac41fc07ab3c 100644
--- a/ui/aura/mus/window_tree_client.cc
+++ b/ui/aura/mus/window_tree_client.cc
@@ -47,6 +47,7 @@
 #include "ui/display/display.h"
 #include "ui/display/screen.h"
 #include "ui/events/event.h"
+#include "ui/events/event_processor.h"
 #include "ui/gfx/geometry/dip_util.h"
 #include "ui/gfx/geometry/insets.h"
 #include "ui/gfx/geometry/size.h"
@@ -1149,14 +1150,10 @@ 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);
-  }
+  // Send the target window that this event should be dispatched to to the event
+  // processor.
+  window->GetWindow()->GetHost()->event_processor()->set_event_target(
+      window->GetWindow());

[sadrul, 2017/02/07 04:04:54]

This is somewhat awkward.

Can we set ui::Event::target_ from here instead? And update the code in
EventProcessor so that it doesn't use the targeter if the event already has a
target set?

[sky, 2017/02/07 04:19:48]

Extremely!
What's wrong with trying to find the location again?

[riajiang, 2017/02/07 17:42:40]

Done! I didn't know we can set the target for an event directly.
But when we create an event from another event (e.g. a mouse event from pointer
event), we don't want to copy over the target right? So I added the target each
time after we do the event conversion... 

 
   EventAckHandler ack_handler(CreateEventResultCallback(event_id));
   // TODO(moshayedi): crbug.com/617222. No need to convert to ui::MouseEvent or