Adds OnChildWindowVisibilityChanged to ui::WindowObserver

services/ui/ws/window_manager_client_unittest.cc

Index: services/ui/ws/window_manager_client_unittest.cc
diff --git a/services/ui/ws/window_manager_client_unittest.cc b/services/ui/ws/window_manager_client_unittest.cc
index 3dea21ef193e4741480ad489e340076ef0551d74..55a370dd3a3894516b84f68621f98d3074da7556 100644
--- a/services/ui/ws/window_manager_client_unittest.cc
+++ b/services/ui/ws/window_manager_client_unittest.cc
@@ -544,7 +544,7 @@ class VisibilityChangeObserver : public WindowObserver {
 
  private:
   // Overridden from WindowObserver:
-  void OnWindowVisibilityChanged(Window* window) override {
+  void OnWindowVisibilityChanged(Window* window, bool visible) override {
     EXPECT_EQ(window, window_);
     EXPECT_TRUE(WindowServerTestBase::QuitRunLoop());
   }