Remove ActiveDOMObject::stop()

third_party/WebKit/Source/modules/presentation/PresentationAvailability.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "modules/presentation/PresentationAvailability.h"
 
 #include "bindings/core/v8/ScriptPromiseResolver.h"
 #include "core/dom/Document.h"
 #include "core/events/Event.h"
 #include "core/frame/UseCounter.h"
 #include "modules/EventTargetModulesNames.h"
 #include "modules/presentation/PresentationController.h"
 #include "public/platform/Platform.h"
 #include "public/platform/modules/presentation/WebPresentationClient.h"
 
 namespace blink {
 
 namespace {
 
 WebPresentationClient* presentationClient(ExecutionContext* executionContext) {
-  ASSERT(executionContext && executionContext->isDocument());
-
+  if (!executionContext)

[dcheng, 2016/10/05 00:10:27]

Is this because we can be asked to provide a presentationClient() for a detached
context? Just curious, but how come we didn't hit this before?

[haraken, 2016/10/05 02:38:24]

You're correct.

We didn't hit this branch before because stop() had been called a bit earlier
than contextDestroyed(), which means that State::Inactive had been set a bit
earlier before.

To mitigate these kinds of subtle timing issues, I'm planning to move
notifyContextDestroyed() to the beginning of Document::shutdown() so that
contextDestroyed() is called earlier (and before Document starts any disruptive
operations).

+    return nullptr;
+  DCHECK(executionContext->isDocument());
   Document* document = toDocument(executionContext);
   if (!document->frame())
     return nullptr;
   PresentationController* controller =
       PresentationController::from(*document->frame());
   return controller ? controller->client() : nullptr;
 }
 
 }  // anonymous namespace
 
@@ skipping 54 matching lines @@
 }
 
 void PresentationAvailability::resume() {
   setState(State::Active);
 }
 
 void PresentationAvailability::suspend() {
   setState(State::Suspended);
 }
 
-void PresentationAvailability::stop() {
+void PresentationAvailability::contextDestroyed() {
   setState(State::Inactive);
 }
 
 void PresentationAvailability::pageVisibilityChanged() {
   if (m_state == State::Inactive)
     return;
   updateListening();
 }
 
 void PresentationAvailability::setState(State state) {
@@ skipping 22 matching lines @@
   return m_value;
 }
 
 DEFINE_TRACE(PresentationAvailability) {
   EventTargetWithInlineData::trace(visitor);
   PageVisibilityObserver::trace(visitor);
   ActiveDOMObject::trace(visitor);
 }
 
 }  // namespace blink