Make Page Visibility API work when the browser window is visible or not

ui/aura/window_unittest.cc

Index: ui/aura/window_unittest.cc
diff --git a/ui/aura/window_unittest.cc b/ui/aura/window_unittest.cc
index fd7ed661229e85c8387aab18d01a4faff0aae78f..25eff9e3191cd8ecc4ea360504cea02f73127f82 100644
--- a/ui/aura/window_unittest.cc
+++ b/ui/aura/window_unittest.cc
@@ -1817,7 +1817,8 @@ class WindowObserverTest : public WindowTest,
 
   void OnWillRemoveWindow(Window* window) override { removed_count_++; }
 
-  void OnWindowVisibilityChanged(Window* window, bool visible) override {
+  void OnWindowVisibilityChanged(Window* window, bool visible,
+      bool content_visible) override {
     if (!visibility_info_) {
       visibility_info_.reset(new VisibilityInfo);
       visibility_info_->changed_count = 0;