Implement a MoveCursorToScreenLocation for just the window manager.

ui/aura/mus/window_tree_host_mus.cc

Index: ui/aura/mus/window_tree_host_mus.cc
diff --git a/ui/aura/mus/window_tree_host_mus.cc b/ui/aura/mus/window_tree_host_mus.cc
index 85cdf6a4dbffecb270771c8ea66f2d378295362c..e3d32ae33c7b66c8bb979457c971a9952cf764af 100644
--- a/ui/aura/mus/window_tree_host_mus.cc
+++ b/ui/aura/mus/window_tree_host_mus.cc
@@ -200,10 +200,11 @@ gfx::ICCProfile WindowTreeHostMus::GetICCProfileForCurrentDisplay() {
 
 void WindowTreeHostMus::MoveCursorToScreenLocationInPixels(
     const gfx::Point& location_in_pixels) {
-  // TODO: this needs to message the server http://crbug.com/693340. Setting
-  // the location is really only appropriate in tests, outside of tests this
-  // value is ignored.
-  NOTIMPLEMENTED();
+  gfx::Point dip_location = location_in_pixels;
+  ConvertScreenInPixelsToDIP(&dip_location);

[riajiang, 2017/06/01 21:27:30]

EventDispatcher::SetMousePointerDisplayLocation expects location to be in
display-coordinate-pixels, maybe skip the dip conversion in
ConvertScreenInPixelsToDIP?

[Elliot Glaysher, 2017/06/01 22:05:23]

Done, though I remain confused about when and where we are using dips vs pixels.
(For example, CursorLocationManager internally says that its using dips, but the
consumer of CursorLocationManger is Env::last_mouse_location() which doesn't
specify the coordinate space; neither does its consumer in
ScreenMus::GetCursorScreenPoint().)

[riajiang, 2017/06/01 22:20:18]

Event root_location has changed to be in pixels in WS. Since 
EventDispatcher::mouse_pointer_last_location_ gets its value
from event root_location it is now also display-coord-pixels. 
CursorLocationManager is an exception where location would be
converted back to screen-coord-dip in 
WindowManagerState::OnMouseCursorLocationChanged before sending
to CursorLocationManager because I think Env::last_mouse_location()
expects mouse location to be in screen-coord-dip.

+  delegate_->OnWindowTreeHostMoveCursorToDisplayLocation(dip_location,
+                                                         display_id_);
+
   Env::GetInstance()->set_last_mouse_location(location_in_pixels);
 }