chromeos: changes how DisplayManagerObservers are notified

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 5b3a58f696fa361a9f21517635a41b0193b70ae6..0b93d12151ebe0240ab582e39b457574bb7d4f01 100644
--- a/ui/aura/mus/window_tree_client.cc
+++ b/ui/aura/mus/window_tree_client.cc
@@ -193,6 +193,12 @@ void DispatchEventToTarget(ui::Event* event, WindowMus* target) {
   GetWindowTreeHostMus(target)->SendEventToSink(event);
 }
 
+// Use for acks from mus that are expected to always succeed and if they don't
+// a crash is triggered.
+void OnAckMustSucceed(bool success) {
+  CHECK(success);
+}
+
 }  // namespace
 
 WindowTreeClient::WindowTreeClient(
@@ -1869,6 +1875,18 @@ void WindowTreeClient::RequestClose(Window* window) {
     window_manager_client_->WmRequestClose(WindowMus::Get(window)->server_id());
 }
 
+void WindowTreeClient::SetDisplayConfiguration(
+    const std::vector<display::Display>& displays,
+    std::vector<ui::mojom::WmViewportMetricsPtr> viewport_metrics,
+    int64_t primary_display_id) {
+  DCHECK_EQ(displays.size(), viewport_metrics.size());
+  if (window_manager_client_) {
+    window_manager_client_->SetDisplayConfiguration(
+        displays, std::move(viewport_metrics), primary_display_id,
+        base::Bind(&OnAckMustSucceed));
+  }
+}
+
 void WindowTreeClient::OnWindowTreeHostBoundsWillChange(
     WindowTreeHostMus* window_tree_host,
     const gfx::Rect& bounds) {