mus: Let clients set the cursor of their window.

components/mus/public/cpp/lib/window_tree_client_impl.cc

Index: components/mus/public/cpp/lib/window_tree_client_impl.cc
diff --git a/components/mus/public/cpp/lib/window_tree_client_impl.cc b/components/mus/public/cpp/lib/window_tree_client_impl.cc
index 163f1a35d31bdc70f3a169568e1c36a8d085bba5..02c35274b097206daf5f8fe5c5664fac4d74231b 100644
--- a/components/mus/public/cpp/lib/window_tree_client_impl.cc
+++ b/components/mus/public/cpp/lib/window_tree_client_impl.cc
@@ -222,6 +222,12 @@ void WindowTreeClientImpl::SetCanFocus(Id window_id, bool can_focus) {
   tree_->SetCanFocus(window_id, can_focus);
 }
 
+void WindowTreeClientImpl::SetStandardCursor(Id window_id,
+                                             mus::mojom::Cursor cursor_id) {
+  DCHECK(tree_);
+  tree_->SetStandardCursor(window_id, cursor_id);
+}
+
 void WindowTreeClientImpl::SetVisible(Id window_id, bool visible) {
   DCHECK(tree_);
   tree_->SetWindowVisibility(window_id, visible, ActionCompletedCallback());
@@ -592,6 +598,15 @@ void WindowTreeClientImpl::OnWindowFocused(Id focused_window_id) {
   }
 }
 
+void WindowTreeClientImpl::OnWindowCursorChanged(Id window_id,
+                                                 mojom::Cursor cursor) {
+  Window* window = GetWindowById(window_id);
+  if (window) {
+    FOR_EACH_OBSERVER(WindowObserver, *WindowPrivate(window).observers(),
+                      OnWindowCursorChanged(window, cursor));
+  }
+}
+
 void WindowTreeClientImpl::OnChangeCompleted(uint32 change_id, bool success) {
   scoped_ptr<InFlightChange> change(std::move(in_flight_map_[change_id]));
   in_flight_map_.erase(change_id);