Media: fix memory leak because of the document holding on an EventListener.

third_party/WebKit/Source/core/html/shadow/MediaControlsMediaEventListener.cpp

Index: third_party/WebKit/Source/core/html/shadow/MediaControlsMediaEventListener.cpp
diff --git a/third_party/WebKit/Source/core/html/shadow/MediaControlsMediaEventListener.cpp b/third_party/WebKit/Source/core/html/shadow/MediaControlsMediaEventListener.cpp
index 7d2034368e868ae6caf1f848d5be7eb40a107a9a..f57ded6fa7a626d3fc0517aaa6d240ae1aa4c367 100644
--- a/third_party/WebKit/Source/core/html/shadow/MediaControlsMediaEventListener.cpp
+++ b/third_party/WebKit/Source/core/html/shadow/MediaControlsMediaEventListener.cpp
@@ -14,6 +14,7 @@ namespace blink {
 MediaControlsMediaEventListener::MediaControlsMediaEventListener(
     MediaControls* mediaControls)
     : EventListener(CPPEventListenerType), m_mediaControls(mediaControls) {
+  LOG(INFO) << "MediaControlsMediaEventListener ctor";
   mediaElement().addEventListener(EventTypeNames::volumechange, this, false);

[Zhiqiang Zhang (Slow), 2017/03/01 16:22:36]

Same concern as MediaControlsOrientationLockDelegate, when we add/remove the
element multiple times, we will create many listeners and they will be always
alive until the element is gc-ed.

[mlamouri (slow - plz ping), 2017/03/01 20:22:33]

Ack.

   mediaElement().addEventListener(EventTypeNames::focusin, this, false);
   mediaElement().addEventListener(EventTypeNames::timeupdate, this, false);
@@ -37,11 +38,26 @@ MediaControlsMediaEventListener::MediaControlsMediaEventListener(
   textTracks->addEventListener(EventTypeNames::removetrack, this, false);
 }
 
+MediaControlsMediaEventListener::~MediaControlsMediaEventListener() {
+  LOG(INFO) << "MediaControlsMediaEventListener dtor";
+}
+
 bool MediaControlsMediaEventListener::operator==(
     const EventListener& other) const {
   return this == &other;
 }
 
+void MediaControlsMediaEventListener::detach() {
+  LOG(INFO) << "MediaControlsMediaEventListener::detach";
+  m_mediaControls->document().removeEventListener(
+      EventTypeNames::fullscreenchange, this, false);
+
+  TextTrackList* textTracks = mediaElement().textTracks();
+  textTracks->removeEventListener(EventTypeNames::addtrack, this, false);
+  textTracks->removeEventListener(EventTypeNames::change, this, false);
+  textTracks->removeEventListener(EventTypeNames::removetrack, this, false);
+}
+
 HTMLMediaElement& MediaControlsMediaEventListener::mediaElement() {
   return m_mediaControls->mediaElement();
 }
@@ -107,6 +123,7 @@ void MediaControlsMediaEventListener::handleEvent(
 }
 
 DEFINE_TRACE(MediaControlsMediaEventListener) {
+  LOG(INFO) << "MediaControlsMediaEventListener::trace";
   EventListener::trace(visitor);
   visitor->trace(m_mediaControls);
 }