Extract simpler classes for observing context lifecycle and observe Page lifecycle inNavigatorVibra…

Source/core/page/Page.cpp

Index: Source/core/page/Page.cpp
diff --git a/Source/core/page/Page.cpp b/Source/core/page/Page.cpp
index 31a8fa12704beb45077e542707626b5e8de7c864..f7d2e784597497e8dcc29052937f7d8e5ccea415 100644
--- a/Source/core/page/Page.cpp
+++ b/Source/core/page/Page.cpp
@@ -45,6 +45,7 @@
 #include "core/page/FrameView.h"
 #include "core/page/PageConsole.h"
 #include "core/page/PageGroup.h"
+#include "core/page/PageLifecycleNotifier.h"
 #include "core/page/PointerLockController.h"
 #include "core/page/Settings.h"
 #include "core/page/scrolling/ScrollingCoordinator.h"
@@ -636,6 +637,9 @@ void Page::setVisibilityState(PageVisibilityState visibilityState, bool isInitia
         return;
     m_visibilityState = visibilityState;
 
+    if (!isInitialState)
+        lifecycleNotifier()->notifyPageVisibilityChanged();
+
     if (!isInitialState && m_mainFrame)
         m_mainFrame->dispatchVisibilityStateChangeEvent();
 
@@ -831,6 +835,16 @@ void Page::multisamplingChanged()
         (*it)->multisamplingChanged(m_settings->openGLMultisamplingEnabled());
 }
 
+PageLifecycleNotifier* Page::lifecycleNotifier()
+{
+    return static_cast<PageLifecycleNotifier*>(LifecycleContext::lifecycleNotifier());
+}
+
+PassOwnPtr<LifecycleNotifier> Page::createLifecycleNotifier()
+{
+    return PageLifecycleNotifier::create(this);
+}
+
 Page::PageClients::PageClients()
     : chromeClient(0)
     , contextMenuClient(0)