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

Source/core/page/PageLifecycleNotifier.cpp

Index: Source/core/page/PageLifecycleNotifier.cpp
diff --git a/Source/core/page/PageLifecycleNotifier.cpp b/Source/core/page/PageLifecycleNotifier.cpp
index 9d50b94f908dce42306c0e4ac3db764cddcd2e46..21e9b5fa5f72ff36782cb6fba2c4939f678db333 100644
--- a/Source/core/page/PageLifecycleNotifier.cpp
+++ b/Source/core/page/PageLifecycleNotifier.cpp
@@ -27,8 +27,6 @@
 #include "config.h"
 #include "core/page/PageLifecycleNotifier.h"
 
-#include "core/page/PageLifecycleObserver.h"
-
 namespace blink {
 
 PageLifecycleNotifier::PageLifecycleNotifier(Page* context)
@@ -56,18 +54,4 @@ void PageLifecycleNotifier::removeObserver(PageLifecycleNotifier::Observer* obse
     LifecycleNotifier<Page>::removeObserver(observer);
 }
 
-void PageLifecycleNotifier::notifyPageVisibilityChanged()
-{
-    TemporaryChange<IterationType> scope(m_iterating, IteratingOverPageObservers);
-    for (PageLifecycleObserver* pageObserver : m_pageObservers)
-        pageObserver->pageVisibilityChanged();
-}
-
-void PageLifecycleNotifier::notifyDidCommitLoad(LocalFrame* frame)
-{
-    TemporaryChange<IterationType> scope(m_iterating, IteratingOverPageObservers);
-    for (PageLifecycleObserver* pageObserver : m_pageObservers)
-        pageObserver->didCommitLoad(frame);
-}
-
 } // namespace blink