Remove unnecessary LifecycleObserver::clearContext

third_party/WebKit/Source/modules/vibration/VibrationController.cpp

Index: third_party/WebKit/Source/modules/vibration/VibrationController.cpp
diff --git a/third_party/WebKit/Source/modules/vibration/VibrationController.cpp b/third_party/WebKit/Source/modules/vibration/VibrationController.cpp
index 87c9eeff61fe11912f3a7231c1a82124d30a37f7..35e4ad17b0bfd721ded3ecaf0e60fdffd8c0df01 100644
--- a/third_party/WebKit/Source/modules/vibration/VibrationController.cpp
+++ b/third_party/WebKit/Source/modules/vibration/VibrationController.cpp
@@ -177,13 +177,6 @@ void VibrationController::contextDestroyed() {
 
   // If the document context was destroyed, never call the mojo service again.
   m_service.reset();
-
-  // The context is not automatically cleared, so do it manually.
-  ContextLifecycleObserver::clearContext();
-
-  // Page outlives ExecutionContext so stop observing it to avoid having
-  // |pageVisibilityChanged| or |contextDestroyed| called again.
-  PageVisibilityObserver::clearContext();

[haraken, 2016/12/19 06:13:13]

Some objects inherit from both ContextLifecycleObserver and
PageVisibilityObserver. The objects override "contextDestroyed", which is called
when the context is detached and the page is detached. This is really
confusing...

We should introduce contextDestroyed, pageDestroyed, workerThreadDestroyed etc
per lifecycle observer.

 }
 
 void VibrationController::pageVisibilityChanged() {