Revert r189385 "Remove LifecycleContext" and r189391, r189530, r189456 that block it

Source/core/page/Page.h

Index: Source/core/page/Page.h
diff --git a/Source/core/page/Page.h b/Source/core/page/Page.h
index de35ed6b897d2691a2e96180047b54913320be70..bc54fe5def8de3f9b3e88a5d5926566ea036b8e2 100644
--- a/Source/core/page/Page.h
+++ b/Source/core/page/Page.h
@@ -26,8 +26,8 @@
 #include "core/frame/SettingsDelegate.h"
 #include "core/frame/UseCounter.h"
 #include "core/page/PageAnimator.h"
-#include "core/page/PageLifecycleNotifier.h"
 #include "core/page/PageVisibilityState.h"
+#include "platform/LifecycleContext.h"
 #include "platform/Supplementable.h"
 #include "platform/geometry/LayoutRect.h"
 #include "platform/geometry/Region.h"
@@ -55,6 +55,7 @@ class Frame;
 class FrameHost;
 class InspectorClient;
 class InspectorController;
+class PageLifecycleNotifier;
 class PluginData;
 class PointerLockController;
 class ScrollingCoordinator;
@@ -67,7 +68,7 @@ typedef uint64_t LinkHash;
 
 float deviceScaleFactor(LocalFrame*);
 
-class Page final : public NoBaseWillBeGarbageCollectedFinalized<Page>, public WillBeHeapSupplementable<Page>, public PageLifecycleNotifier, public SettingsDelegate {
+class Page final : public NoBaseWillBeGarbageCollectedFinalized<Page>, public WillBeHeapSupplementable<Page>, public LifecycleContext<Page>, public SettingsDelegate {
     WILL_BE_USING_GARBAGE_COLLECTED_MIXIN(Page);
     WTF_MAKE_NONCOPYABLE(Page);
     friend class Settings;
@@ -197,10 +198,14 @@ public:
     void acceptLanguagesChanged();
 
     static void networkStateChanged(bool online);
+    PassOwnPtr<LifecycleNotifier<Page>> createLifecycleNotifier();
 
     void trace(Visitor*);
     void willBeDestroyed();
 
+protected:
+    PageLifecycleNotifier& lifecycleNotifier();
+
 private:
     void initGroup();