Wires up WindowTreeClient::SetDisplayRoot()

ui/aura/test/mus/window_tree_client_private.h

Index: ui/aura/test/mus/window_tree_client_private.h
diff --git a/ui/aura/test/mus/window_tree_client_private.h b/ui/aura/test/mus/window_tree_client_private.h
index 3c2279df44f4acca272bfef84588d640ec7cd7a6..b0ad445818a13e7373d399ed496317972e910b24 100644
--- a/ui/aura/test/mus/window_tree_client_private.h
+++ b/ui/aura/test/mus/window_tree_client_private.h
@@ -31,6 +31,8 @@ class Window;
 class WindowTreeClient;
 class WindowTreeHostMus;
 
+struct WindowTreeHostMusInitParams;
+
 // Use to access implementation details of WindowTreeClient.
 class WindowTreeClientPrivate {
  public:
@@ -57,6 +59,8 @@ class WindowTreeClientPrivate {
 
   void CallOnConnect();
 
+  WindowTreeHostMusInitParams CallCreateInitParamsForNewDisplay();
+
   // Sets the WindowTree and client id.
   void SetTreeAndClientId(ui::mojom::WindowTree* window_tree,
                           ClientSpecificId client_id);