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 a022a6b8d2e483a3af6734474e96ac0bd1d7275b..7f3c39367788fea3a812c05568c02e7df6b0cb24 100644
--- a/Source/core/page/Page.cpp
+++ b/Source/core/page/Page.cpp
@@ -44,6 +44,7 @@
 #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"
@@ -625,6 +626,9 @@ void Page::setVisibilityState(PageVisibilityState visibilityState, bool isInitia
     else
         setTimerAlignmentInterval(DOMTimer::visiblePageAlignmentInterval());
 
+    if (!isInitialState)
+        lifecycleNotifier()->notifyPageVisibilityChanged();
+
     if (!isInitialState && m_mainFrame)
         m_mainFrame->dispatchVisibilityStateChangeEvent();
 }
@@ -783,6 +787,16 @@ 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)