Remove MediaControls methods needed for the Cast button

third_party/WebKit/Source/modules/remoteplayback/RemotePlaybackTest.cpp

 // Copyright 2016 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/remoteplayback/RemotePlayback.h"
 
 #include "bindings/core/v8/ExceptionState.h"
 #include "bindings/core/v8/V8BindingForTesting.h"
 #include "bindings/modules/v8/RemotePlaybackAvailabilityCallback.h"
 #include "core/dom/DocumentUserGestureToken.h"
@@ skipping 38 matching lines @@
 
 class RemotePlaybackTest : public ::testing::Test {
  protected:
   void CancelPrompt(RemotePlayback* remote_playback) {
     remote_playback->PromptCancelled();
   }
 
   void SetState(RemotePlayback* remote_playback, WebRemotePlaybackState state) {
     remote_playback->StateChanged(state);
   }
+
+  bool HasAvailabilityCallbacks(RemotePlayback* remote_playback) {
+    return !remote_playback->availability_callbacks_.IsEmpty();
+  }
 };
 
 TEST_F(RemotePlaybackTest, PromptCancelledRejectsWithNotAllowedError) {
   V8TestingScope scope;
 
   auto page_holder = DummyPageHolder::Create();
 
   HTMLMediaElement* element =
       HTMLVideoElement::Create(page_holder->GetDocument());
   RemotePlayback* remote_playback =
@@ skipping 197 matching lines @@
   // Runs pending promises.
   v8::MicrotasksScope::PerformCheckpoint(scope.GetIsolate());
 
   // Verify mock expectations explicitly as the mock objects are garbage
   // collected.
   ::testing::Mock::VerifyAndClear(resolve);
   ::testing::Mock::VerifyAndClear(reject);
   ::testing::Mock::VerifyAndClear(callback_function);
 }
 
+TEST_F(RemotePlaybackTest, RemovingFromDocumentRemovesListenersAndCallbacks) {
+  V8TestingScope scope;
+
+  auto page_holder = DummyPageHolder::Create();
+
+  HTMLMediaElement* element =
+      HTMLVideoElement::Create(page_holder->GetDocument());
+  element->SetBooleanAttribute(HTMLNames::controlsAttr, true);
+  page_holder->GetDocument().body()->AppendChild(element);
+
+  RemotePlayback* remote_playback =
+      HTMLMediaElementRemotePlayback::remote(*element);
+
+  EXPECT_TRUE(remote_playback->HasEventListeners());
+  EXPECT_TRUE(HasAvailabilityCallbacks(remote_playback));
+
+  WeakPersistent<HTMLMediaElement> weak_persistent_video = element;
+  {
+    Persistent<HTMLMediaElement> persistent_video = element;
+    page_holder->GetDocument().body()->setInnerHTML("");
+
+    // When removed from the document, the event listeners should have been
+    // dropped.
+    EXPECT_FALSE(remote_playback->HasEventListeners());
+    EXPECT_FALSE(HasAvailabilityCallbacks(remote_playback));
+  }
+
+  ThreadState::Current()->CollectAllGarbage();
+
+  // It has been GC'd.
+  EXPECT_EQ(nullptr, weak_persistent_video);

[whywhat, 2017/04/24 23:59:29]

Kentaro, this fails (and a similar test in existing
HTMLMediaElementEventListenersTest.cpp).

As I understand it, the reference chain is the following:

HTMLMediaElement -> Member<MediaControls> ->
Member<MediaControlsMediaEventListeners> -> Member<RemotePlayback> ->
HeapHashMap<int, Member<AvailabilityCallback>> -> unique_ptr<WTF::Closure> ->
WrapPersistent<MediaControlsMediaEventListeners> -> Member<MediaControls> etc.

If I don't register the WTF::Closure with RemotePlayback, the tests pass.
How should I handle the WTF::Closure correctly so that GC works?

I assumed that once the Member<AvailabilityCallback> is removed from the
HeapHashMap, it is unreachable and should be GCed. However it doesn't seem to
free the unique_ptr to WTF::Closure or something and that keeps a persistent
reference to the whole graph of traceable objects.

I tried changing it to WrapWeakPersistent() or even call Cancel() on
AvailabilityCallback that would reset unique_ptr but it didn't help :/

+}
+
+TEST_F(RemotePlaybackTest, ReInsertingInDocumentRestoresListenersAndCallbacks) {
+  V8TestingScope scope;
+
+  auto page_holder = DummyPageHolder::Create();
+
+  HTMLMediaElement* element =
+      HTMLVideoElement::Create(page_holder->GetDocument());
+  element->SetBooleanAttribute(HTMLNames::controlsAttr, true);
+  page_holder->GetDocument().body()->AppendChild(element);
+
+  RemotePlayback* remote_playback =
+      HTMLMediaElementRemotePlayback::remote(*element);
+
+  // This should be a no-op. We keep a reference on the media element to avoid
+  // an unexpected GC.
+  {
+    Persistent<HTMLMediaElement> video_holder = element;
+    page_holder->GetDocument().body()->RemoveChild(element);
+    page_holder->GetDocument().body()->AppendChild(video_holder.Get());
+    EXPECT_TRUE(remote_playback->HasEventListeners());
+    EXPECT_TRUE(HasAvailabilityCallbacks(remote_playback));
+  }
+}
+
 }  // namespace blink