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 2b094e96cdc0aa071aa8b3cd18e2d40e3d0b7f0d..b67d4b0e8ca09020ad44b2aebcd8e1188b12cdfb 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 +222,20 @@ void WindowTreeClientImpl::SetCanFocus(Id window_id, bool can_focus) {
   tree_->SetCanFocus(window_id, can_focus);
 }
 
+void WindowTreeClientImpl::SetPredefinedCursor(Id window_id,
+                                               mus::mojom::Cursor cursor_id) {
+  DCHECK(tree_);
+
+  Window* window = GetWindowById(window_id);
+  if (!window)
+    return;
+
+  // We make an inflight change thing here.
+  const uint32_t change_id = ScheduleInFlightChange(make_scoped_ptr(
+      new InFlightPredefinedCursorChange(window, window->predefined_cursor())));
+  tree_->SetPredefinedCursor(change_id, window_id, cursor_id);
+}
+
 void WindowTreeClientImpl::SetVisible(Window* window, bool visible) {
   DCHECK(tree_);
   const uint32_t change_id = ScheduleInFlightChange(
@@ -597,6 +611,16 @@ void WindowTreeClientImpl::OnWindowFocused(Id focused_window_id) {
   }
 }
 
+void WindowTreeClientImpl::OnWindowPredefinedCursorChanged(
+    Id window_id,
+    mojom::Cursor cursor) {
+  Window* window = GetWindowById(window_id);
+  if (window) {
+    FOR_EACH_OBSERVER(WindowObserver, *WindowPrivate(window).observers(),

[sky, 2015/12/03 22:01:10]

You need two things here:
1. If there is an in flight cursor change, you need to merge with it. See
OnWindowBoundsChanged for an example of what I mean.
2. Potentially set the cursor value locally. Again, follow the modle of
OnWindowBoundsChanged.

[Elliot Glaysher, 2015/12/03 22:32:00]

Done. (I think.)

+                      OnWindowPredefinedCursorChanged(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);