Reland: mus: Enable system modal windows

components/mus/ws/test_utils.h

Index: components/mus/ws/test_utils.h
diff --git a/components/mus/ws/test_utils.h b/components/mus/ws/test_utils.h
index f764f950c37ddab2e8525a07da3fac705699c1ca..a2b03a80adbd492c577d44e32adc7e3baa183636 100644
--- a/components/mus/ws/test_utils.h
+++ b/components/mus/ws/test_utils.h
@@ -111,10 +111,11 @@ class EventDispatcherTestApi {
 
   bool AreAnyPointersDown() const { return ed_->AreAnyPointersDown(); }
   bool is_mouse_button_down() const { return ed_->mouse_button_down_; }
-  bool IsObservingWindow(ServerWindow* window) {
-    return ed_->IsObservingWindow(window);
-  }
+  bool IsWindowPointerTarget(const ServerWindow* window) const;
   int NumberPointerTargetsForWindow(ServerWindow* window);
+  ModalWindowController* modal_window_controller() const {
+    return &ed_->modal_window_controller_;
+  }
 
  private:
   EventDispatcher* ed_;
@@ -124,6 +125,24 @@ class EventDispatcherTestApi {
 
 // -----------------------------------------------------------------------------
 
+class ModalWindowControllerTestApi {
+ public:
+  explicit ModalWindowControllerTestApi(ModalWindowController* mwc)
+      : mwc_(mwc) {}
+  ~ModalWindowControllerTestApi() {}
+
+  ServerWindow* GetActiveSystemModalWindow() const {
+    return mwc_->GetActiveSystemModalWindow();
+  }
+
+ private:
+  ModalWindowController* mwc_;
+
+  DISALLOW_COPY_AND_ASSIGN(ModalWindowControllerTestApi);
+};
+
+// -----------------------------------------------------------------------------
+
 class WindowManagerStateTestApi {
  public:
   explicit WindowManagerStateTestApi(WindowManagerState* wms) : wms_(wms) {}