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

ui/views/controls/native/native_view_host_aura_unittest.cc

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/views/controls/native/native_view_host_aura.h"
 
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 #include "ui/aura/client/aura_constants.h"
 #include "ui/aura/window.h"
@@ skipping 27 matching lines @@
       return type != rhs.type || window != rhs.window || bounds != rhs.bounds;
     }
   };
 
   NativeViewHostWindowObserver() {}
   ~NativeViewHostWindowObserver() override {}
 
   const std::vector<EventDetails>& events() const { return events_; }
 
   // aura::WindowObserver overrides
-  void OnWindowVisibilityChanged(aura::Window* window, bool visible) override {
+  void OnWindowVisibilityChanged(aura::Window* window, bool visible,
+      bool content_visible) override {
     EventDetails event;
     event.type = visible ? EVENT_SHOWN : EVENT_HIDDEN;
     event.window = window;
     event.bounds = window->GetBoundsInRootWindow();
 
     // Dedupe events as a single Hide() call can result in several
     // notifications.
     if (events_.size() == 0u || events_.back() != event)
       events_.push_back(event);
   }
@@ skipping 281 matching lines @@
 
   host()->SetVisible(false);
   EXPECT_FALSE(clipping_window()->IsVisible());
   EXPECT_FALSE(child()->IsVisible());
 
   DestroyHost();
   DestroyTopLevel();
 }
 
 }  // namespace views