[Blink>MediaSession] Use setActionCallback() instead of event listeners for media control actions

As the MediaSession spec changed from using event-listener-based
to callback-based fashion for media controls, we need to keep the
implementation up to date.

Spec PR:
https://github.com/WICG/mediasession/pull/159

BUG=675963

Review-Url: https://codereview.chromium.org/2589893002
Cr-Commit-Position: refs/heads/master@{#441787}

third_party/WebKit/LayoutTests/fast/dom/Window/property-access-on-cached-properties-after-frame-navigated-expected.txt

@@ -48,12 +48,6 @@ PASS window.cached_navigator_connection.onchange is null
 PASS window.cached_navigator_connection.ontypechange is null
 PASS window.cached_navigator_mediaDevices.ondevicechange is null
 PASS window.cached_navigator_mediaSession.metadata is null
-PASS window.cached_navigator_mediaSession.onnexttrack is null
-PASS window.cached_navigator_mediaSession.onpause is null
-PASS window.cached_navigator_mediaSession.onplay is null
-PASS window.cached_navigator_mediaSession.onprevioustrack is null
-PASS window.cached_navigator_mediaSession.onseekbackward is null
-PASS window.cached_navigator_mediaSession.onseekforward is null
 PASS window.cached_navigator_mediaSession.playbackState is 'none'
 PASS window.cached_navigator_presentation.defaultRequest is null
 PASS window.cached_navigator_presentation.receiver is null

third_party/WebKit/LayoutTests/fast/dom/Window/property-access-on-cached-properties-after-frame-removed-and-gced-expected.txt

@@ -48,12 +48,6 @@ PASS window.cached_navigator_connection.onchange is null
 PASS window.cached_navigator_connection.ontypechange is null
 PASS window.cached_navigator_mediaDevices.ondevicechange is null
 PASS window.cached_navigator_mediaSession.metadata is null
-PASS window.cached_navigator_mediaSession.onnexttrack is null
-PASS window.cached_navigator_mediaSession.onpause is null
-PASS window.cached_navigator_mediaSession.onplay is null
-PASS window.cached_navigator_mediaSession.onprevioustrack is null
-PASS window.cached_navigator_mediaSession.onseekbackward is null
-PASS window.cached_navigator_mediaSession.onseekforward is null
 PASS window.cached_navigator_mediaSession.playbackState is 'none'
 PASS window.cached_navigator_presentation.defaultRequest is null
 PASS window.cached_navigator_presentation.receiver is null

third_party/WebKit/LayoutTests/fast/dom/Window/property-access-on-cached-properties-after-frame-removed-expected.txt

@@ -48,12 +48,6 @@ PASS window.cached_navigator_connection.onchange is null
 PASS window.cached_navigator_connection.ontypechange is null
 PASS window.cached_navigator_mediaDevices.ondevicechange is null
 PASS window.cached_navigator_mediaSession.metadata is null
-PASS window.cached_navigator_mediaSession.onnexttrack is null
-PASS window.cached_navigator_mediaSession.onpause is null
-PASS window.cached_navigator_mediaSession.onplay is null
-PASS window.cached_navigator_mediaSession.onprevioustrack is null
-PASS window.cached_navigator_mediaSession.onseekbackward is null
-PASS window.cached_navigator_mediaSession.onseekforward is null
 PASS window.cached_navigator_mediaSession.playbackState is 'none'
 PASS window.cached_navigator_presentation.defaultRequest is null
 PASS window.cached_navigator_presentation.receiver is null

third_party/WebKit/LayoutTests/fast/dom/Window/property-access-on-cached-window-after-frame-navigated-expected.txt

@@ -50,12 +50,6 @@ PASS oldChildWindow.navigator.language is newChildWindow.navigator.language
 PASS oldChildWindow.navigator.maxTouchPoints is newChildWindow.navigator.maxTouchPoints
 PASS oldChildWindow.navigator.mediaDevices.ondevicechange is newChildWindow.navigator.mediaDevices.ondevicechange
 PASS oldChildWindow.navigator.mediaSession.metadata is newChildWindow.navigator.mediaSession.metadata
-PASS oldChildWindow.navigator.mediaSession.onnexttrack is newChildWindow.navigator.mediaSession.onnexttrack
-PASS oldChildWindow.navigator.mediaSession.onpause is newChildWindow.navigator.mediaSession.onpause
-PASS oldChildWindow.navigator.mediaSession.onplay is newChildWindow.navigator.mediaSession.onplay
-PASS oldChildWindow.navigator.mediaSession.onprevioustrack is newChildWindow.navigator.mediaSession.onprevioustrack
-PASS oldChildWindow.navigator.mediaSession.onseekbackward is newChildWindow.navigator.mediaSession.onseekbackward
-PASS oldChildWindow.navigator.mediaSession.onseekforward is newChildWindow.navigator.mediaSession.onseekforward
 PASS oldChildWindow.navigator.mediaSession.playbackState is newChildWindow.navigator.mediaSession.playbackState
 PASS oldChildWindow.navigator.onLine is newChildWindow.navigator.onLine
 PASS oldChildWindow.navigator.platform is newChildWindow.navigator.platform

third_party/WebKit/LayoutTests/fast/dom/Window/property-access-on-cached-window-after-frame-removed-and-gced-expected.txt

@@ -29,12 +29,6 @@ PASS childWindow.navigator.language is window.navigator.language
 PASS childWindow.navigator.maxTouchPoints is 0
 PASS childWindow.navigator.mediaDevices.ondevicechange is null
 PASS childWindow.navigator.mediaSession.metadata is null
-PASS childWindow.navigator.mediaSession.onnexttrack is null
-PASS childWindow.navigator.mediaSession.onpause is null
-PASS childWindow.navigator.mediaSession.onplay is null
-PASS childWindow.navigator.mediaSession.onprevioustrack is null
-PASS childWindow.navigator.mediaSession.onseekbackward is null
-PASS childWindow.navigator.mediaSession.onseekforward is null
 PASS childWindow.navigator.mediaSession.playbackState is 'none'
 PASS childWindow.navigator.onLine is window.navigator.onLine
 PASS childWindow.navigator.platform is window.navigator.platform

third_party/WebKit/LayoutTests/fast/dom/Window/property-access-on-cached-window-after-frame-removed-expected.txt

@@ -29,12 +29,6 @@ PASS childWindow.navigator.language is window.navigator.language
 PASS childWindow.navigator.maxTouchPoints is 0
 PASS childWindow.navigator.mediaDevices.ondevicechange is null
 PASS childWindow.navigator.mediaSession.metadata is null
-PASS childWindow.navigator.mediaSession.onnexttrack is null
-PASS childWindow.navigator.mediaSession.onpause is null
-PASS childWindow.navigator.mediaSession.onplay is null
-PASS childWindow.navigator.mediaSession.onprevioustrack is null
-PASS childWindow.navigator.mediaSession.onseekbackward is null
-PASS childWindow.navigator.mediaSession.onseekforward is null
 PASS childWindow.navigator.mediaSession.playbackState is 'none'
 PASS childWindow.navigator.onLine is window.navigator.onLine
 PASS childWindow.navigator.platform is window.navigator.platform

third_party/WebKit/LayoutTests/media/mediasession/mediasession-setactionhandler.html

+<!DOCTYPE html>
+<title>Test that setting MediaSession event handler should notify the service</title>
+<script src="../../resources/testharness.js"></script>
+<script src="../../resources/testharnessreport.js"></script>
+<script>
+
+test(function(t) {
+  window.navigator.mediaSession.setActionHandler("play", null);
+  window.navigator.mediaSession.setActionHandler("pause", null);
+  window.navigator.mediaSession.setActionHandler("previoustrack", null);
+  window.navigator.mediaSession.setActionHandler("nexttrack", null);
+  window.navigator.mediaSession.setActionHandler("seekbackward", null);
+  window.navigator.mediaSession.setActionHandler("seekforward", null);
+}, "Test that setActionHandler() can be executed for supported actions");
+
+test(function(t) {
+  assert_throws(
+      new TypeError("Failed to execute 'setActionHandler' on 'MediaSession':" +
+                    "The provided value 'invalid' is not a valid enum value" +
+                    "of type MediaSessionAction."),
+      _ => { window.navigator.mediaSession.setActionHandler("invalid", null); });
+}, "Test that setActionHandler() throws exception for unsupported actions");
+
+</script>

third_party/WebKit/LayoutTests/media/mediasession/mojo/callback-alive-after-gc.html

+<!DOCTYPE html>
+<title>Test that setting MediaSession callbacks are alive after garbage-collection</title>
+<script src="../../../resources/testharness.js"></script>
+<script src="../../../resources/testharnessreport.js"></script>
+<script src="../../../resources/mojo-helpers.js"></script>
+<script src="resources/mediasessionservice-mock.js"></script>
+<script src="resources/utils.js"></script>
+<script>
+
+var mock;
+
+function gc() {
+  if (window.GCController) {
+    GCController.collect();
+  } else {
+    for (var i = 0; i < 10000; ++i) {
+      ({ });
+    }
+  }
+}
+
+async_test(function(t) {
+  mediaSessionServiceMock.then(m => {
+    mock = m;
+    mock.setClientCallback(_ => {
+      gc();
+      setTimeout(_ => {
+        mock.getClient().didReceiveAction(MediaSessionAction.PLAY);
+      });
+    });
+    window.navigator.mediaSession.setActionHandler("play", _ => { t.done(); });
+  });
+});
+</script>

third_party/WebKit/LayoutTests/media/mediasession/mojo/media-control-action-reaches-client.html

@@ -20,20 +20,26 @@ var expectations = [
 
 var nextExpectation = 0;
 
-function checkExpectation(t, event) {
+function checkExpectation(t, action) {
   var expectedEvent = expectations[nextExpectation];
-  assert_equals(expectedEvent, event.type);
+  assert_equals(expectedEvent, action);
   if (++nextExpectation >= expectations.length)
     t.done();
 }
 
 function runTests(t) {
-  window.navigator.mediaSession.onplay = t.step_func(checkExpectation.bind(null, t));
-  window.navigator.mediaSession.onpause = t.step_func(checkExpectation.bind(null, t));
-  window.navigator.mediaSession.onprevioustrack = t.step_func(checkExpectation.bind(null, t));
-  window.navigator.mediaSession.onnexttrack = t.step_func(checkExpectation.bind(null, t));
-  window.navigator.mediaSession.onseekforward = t.step_func(checkExpectation.bind(null, t));
-  window.navigator.mediaSession.onseekbackward = t.step_func(checkExpectation.bind(null, t));
+  window.navigator.mediaSession.setActionHandler(
+      "play", t.step_func(checkExpectation.bind(null, t, "play")));
+  window.navigator.mediaSession.setActionHandler(
+      "pause", t.step_func(checkExpectation.bind(null, t, "pause")));
+  window.navigator.mediaSession.setActionHandler(
+      "previoustrack", t.step_func(checkExpectation.bind(null, t, "previoustrack")));
+  window.navigator.mediaSession.setActionHandler(
+      "nexttrack", t.step_func(checkExpectation.bind(null, t, "nexttrack")));
+  window.navigator.mediaSession.setActionHandler(
+      "seekbackward", t.step_func(checkExpectation.bind(null, t, "seekbackward")));
+  window.navigator.mediaSession.setActionHandler(
+      "seekforward", t.step_func(checkExpectation.bind(null, t, "seekforward")));
 
   mock.getClient().didReceiveAction(MediaSessionAction.PLAY);
   mock.getClient().didReceiveAction(MediaSessionAction.PAUSE);

third_party/WebKit/LayoutTests/media/mediasession/mojo/media-control-set-handler-notifies-service.html

@@ -22,23 +22,17 @@ function getExpectations() {
       [ MediaSessionAction.SEEK_BACKWARD, true ],
       [ MediaSessionAction.SEEK_FORWARD, true ],
       [ MediaSessionAction.PLAY, false ],
-      [ MediaSessionAction.PLAY, true ],
       [ MediaSessionAction.PAUSE, false ],
-      [ MediaSessionAction.PAUSE, true ],
       [ MediaSessionAction.PREVIOUS_TRACK, false ],
-      [ MediaSessionAction.PREVIOUS_TRACK, true ],
       [ MediaSessionAction.NEXT_TRACK, false ],
-      [ MediaSessionAction.NEXT_TRACK, true ],
       [ MediaSessionAction.SEEK_BACKWARD, false ],
-      [ MediaSessionAction.SEEK_BACKWARD, true ],
       [ MediaSessionAction.SEEK_FORWARD, false ],
+      [ MediaSessionAction.PLAY, true ],
+      [ MediaSessionAction.PAUSE, true ],
+      [ MediaSessionAction.PREVIOUS_TRACK, true ],
+      [ MediaSessionAction.NEXT_TRACK, true ],
+      [ MediaSessionAction.SEEK_BACKWARD, true ],
       [ MediaSessionAction.SEEK_FORWARD, true ],
-      [ MediaSessionAction.PLAY, false ],
-      [ MediaSessionAction.PAUSE, false ],
-      [ MediaSessionAction.PREVIOUS_TRACK, false ],
-      [ MediaSessionAction.NEXT_TRACK, false ],
-      [ MediaSessionAction.SEEK_BACKWARD, false ],
-      [ MediaSessionAction.SEEK_FORWARD, false ],
     ];
   }
   return expectations;
@@ -55,32 +49,45 @@ async_test(function(t) {
         t.done();
     }));
 
-    // Setting handlers
-    window.navigator.mediaSession.onresize = _ => {};  // Unknown event.
-    window.navigator.mediaSession.onplay = _ => {};
-    window.navigator.mediaSession.onpause = _ => {};
-    window.navigator.mediaSession.onprevioustrack = _ => {};
-    window.navigator.mediaSession.onnexttrack = _ => {};
-    window.navigator.mediaSession.onseekbackward = _ => {};
-    window.navigator.mediaSession.onseekforward = _ => {};
+    // Setting handlers should notify the service.
+    window.navigator.mediaSession.setActionHandler("play", _ => {});
+    window.navigator.mediaSession.setActionHandler("pause", _ => {});
+    window.navigator.mediaSession.setActionHandler("previoustrack", _ => {});
+    window.navigator.mediaSession.setActionHandler("nexttrack", _ => {});
+    window.navigator.mediaSession.setActionHandler("seekbackward", _ => {});
+    window.navigator.mediaSession.setActionHandler("seekforward", _ => {});
+
+    // Setting handlers again should not notify the service.
+    window.navigator.mediaSession.setActionHandler("play", _ => {});
+    window.navigator.mediaSession.setActionHandler("pause", _ => {});
+    window.navigator.mediaSession.setActionHandler("previoustrack", _ => {});
+    window.navigator.mediaSession.setActionHandler("nexttrack", _ => {});
+    window.navigator.mediaSession.setActionHandler("seekbackward", _ => {});
+    window.navigator.mediaSession.setActionHandler("seekforward", _ => {});
+
+    // Unsetting handlers should notify the service.
+    window.navigator.mediaSession.setActionHandler("play", null);
+    window.navigator.mediaSession.setActionHandler("pause", null);
+    window.navigator.mediaSession.setActionHandler("previoustrack", null);
+    window.navigator.mediaSession.setActionHandler("nexttrack", null);
+    window.navigator.mediaSession.setActionHandler("seekbackward", null);
+    window.navigator.mediaSession.setActionHandler("seekforward", null);
 
-    // Resetting handlers
-    window.navigator.mediaSession.onresize = _ => {};  // Unknown event.
-    window.navigator.mediaSession.onplay = _ => {};
-    window.navigator.mediaSession.onpause = _ => {};
-    window.navigator.mediaSession.onprevioustrack = _ => {};
-    window.navigator.mediaSession.onnexttrack = _ => {};
-    window.navigator.mediaSession.onseekbackward = _ => {};
-    window.navigator.mediaSession.onseekforward = _ => {};
+    // Unsetting handlers should not notify the service.
+    window.navigator.mediaSession.setActionHandler("play", null);
+    window.navigator.mediaSession.setActionHandler("pause", null);
+    window.navigator.mediaSession.setActionHandler("previoustrack", null);
+    window.navigator.mediaSession.setActionHandler("nexttrack", null);
+    window.navigator.mediaSession.setActionHandler("seekbackward", null);
+    window.navigator.mediaSession.setActionHandler("seekforward", null);
 
-    // Unsetting handlers
-    window.navigator.mediaSession.onresize = null;  // Unknown event.
-    window.navigator.mediaSession.onplay = null;
-    window.navigator.mediaSession.onpause = null;
-    window.navigator.mediaSession.onprevioustrack = null;
-    window.navigator.mediaSession.onnexttrack = null;
-    window.navigator.mediaSession.onseekbackward = null;
-    window.navigator.mediaSession.onseekforward = null;
+    // Setting handlers again should notify the service.
+    window.navigator.mediaSession.setActionHandler("play", _ => {});
+    window.navigator.mediaSession.setActionHandler("pause", _ => {});
+    window.navigator.mediaSession.setActionHandler("previoustrack", _ => {});
+    window.navigator.mediaSession.setActionHandler("nexttrack", _ => {});
+    window.navigator.mediaSession.setActionHandler("seekbackward", _ => {});
+    window.navigator.mediaSession.setActionHandler("seekforward", _ => {});
   });
 }, "test that setting event handler notifies the mojo service");
 

third_party/WebKit/LayoutTests/webexposed/global-interface-listing-expected.txt

@@ -3933,21 +3933,10 @@ interface MediaRecorder : EventTarget
 interface MediaSession : EventTarget
     attribute @@toStringTag
     getter metadata
-    getter onnexttrack
-    getter onpause
-    getter onplay
-    getter onprevioustrack
-    getter onseekbackward
-    getter onseekforward
     getter playbackState
     method constructor
+    method setActionHandler
     setter metadata
-    setter onnexttrack
-    setter onpause
-    setter onplay
-    setter onprevioustrack
-    setter onseekbackward
-    setter onseekforward
     setter playbackState
 interface MediaSettingsRange
     attribute @@toStringTag

third_party/WebKit/Source/bindings/modules/v8/custom/V8MediaSessionCustom.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 "bindings/modules/v8/V8MediaSession.h"
+
+#include "bindings/core/v8/V8DOMWrapper.h"
+#include "modules/mediasession/MediaSession.h"
+
+namespace blink {
+
+void V8MediaSession::visitDOMWrapperCustom(
+    v8::Isolate* isolate,
+    ScriptWrappable* scriptWrappable,
+    const v8::Persistent<v8::Object>& wrapper) {
+  scriptWrappable->toImpl<MediaSession>()->setV8ReferencesForHandlers(isolate,
+                                                                      wrapper);
+}
+
+}  // namespace blink

third_party/WebKit/Source/bindings/modules/v8/custom/custom.gni

@@ -9,6 +9,7 @@ bindings_modules_v8_custom_files =
                     "V8DeviceMotionEventCustom.cpp",
                     "V8ExtendableMessageEventCustom.cpp",
                     "V8IDBObserverCustom.cpp",
+                    "V8MediaSessionCustom.cpp",
                     "V8RemotePlaybackCustom.cpp",
                     "V8WebGLRenderingContextCustom.cpp",
                     "V8WebGL2RenderingContextCustom.cpp",

third_party/WebKit/Source/bindings/modules/v8/generated.gni

@@ -65,6 +65,8 @@ bindings_modules_generated_union_type_files = [
 generated_modules_callback_function_files = [
   "$bindings_modules_v8_output_dir/IDBObserverCallback.cpp",
   "$bindings_modules_v8_output_dir/IDBObserverCallback.h",
+  "$bindings_modules_v8_output_dir/MediaSessionActionHandler.cpp",
+  "$bindings_modules_v8_output_dir/MediaSessionActionHandler.h",
   "$bindings_modules_v8_output_dir/RemotePlaybackAvailabilityCallback.cpp",
   "$bindings_modules_v8_output_dir/RemotePlaybackAvailabilityCallback.h",
 ]

third_party/WebKit/Source/core/events/EventTypeNames.in

@@ -151,7 +151,6 @@ mouseup
 mousewheel
 mute
 negotiationneeded
-nexttrack
 nomatch
 notificationclick
 notificationclose
@@ -170,7 +169,6 @@ paymentrequest
 periodicsync
 play
 playing
-playpause
 pointercancel
 pointerdown
 pointerenter
@@ -182,7 +180,6 @@ pointerout
 pointerover
 pointerup
 popstate
-previoustrack
 progress
 push
 ratechange
@@ -200,9 +197,7 @@ resume
 scroll
 search
 securitypolicyviolation
-seekbackward
 seeked
-seekforward
 seeking
 select
 selectionchange

third_party/WebKit/Source/modules/EventTargetModulesFactory.in

@@ -14,7 +14,6 @@ modules/indexeddb/IDBOpenDBRequest
 modules/indexeddb/IDBRequest
 modules/indexeddb/IDBTransaction
 modules/mediarecorder/MediaRecorder
-modules/mediasession/MediaSession
 modules/mediasource/MediaSource
 modules/mediasource/SourceBuffer
 modules/mediasource/SourceBufferList

third_party/WebKit/Source/modules/mediasession/MediaSession.cpp

@@ -4,12 +4,11 @@
 
 #include "modules/mediasession/MediaSession.h"
 
+#include "bindings/modules/v8/MediaSessionActionHandler.h"
 #include "core/dom/Document.h"
 #include "core/dom/DocumentUserGestureToken.h"
 #include "core/dom/ExecutionContext.h"
-#include "core/events/Event.h"
 #include "core/frame/LocalFrame.h"
-#include "modules/EventTargetModules.h"
 #include "modules/mediasession/MediaMetadata.h"
 #include "modules/mediasession/MediaMetadataSanitizer.h"
 #include "platform/UserGestureIndicator.h"
@@ -23,39 +22,49 @@ namespace {
 
 using ::blink::mojom::blink::MediaSessionAction;
 
-const AtomicString& mojomActionToEventName(MediaSessionAction action) {
+const AtomicString& mojomActionToActionName(MediaSessionAction action) {
+  DEFINE_STATIC_LOCAL(const AtomicString, playActionName, ("play"));
+  DEFINE_STATIC_LOCAL(const AtomicString, pauseActionName, ("pause"));
+  DEFINE_STATIC_LOCAL(const AtomicString, previousTrackActionName,
+                      ("previoustrack"));
+  DEFINE_STATIC_LOCAL(const AtomicString, nextTrackActionName, ("nexttrack"));
+  DEFINE_STATIC_LOCAL(const AtomicString, seekBackwardActionName,
+                      ("seekbackward"));
+  DEFINE_STATIC_LOCAL(const AtomicString, seekForwardActionName,
+                      ("seekforward"));
+
   switch (action) {
     case MediaSessionAction::PLAY:
-      return EventTypeNames::play;
+      return playActionName;
     case MediaSessionAction::PAUSE:
-      return EventTypeNames::pause;
+      return pauseActionName;
     case MediaSessionAction::PREVIOUS_TRACK:
-      return EventTypeNames::previoustrack;
+      return previousTrackActionName;
     case MediaSessionAction::NEXT_TRACK:
-      return EventTypeNames::nexttrack;
+      return nextTrackActionName;
     case MediaSessionAction::SEEK_BACKWARD:
-      return EventTypeNames::seekbackward;
+      return seekBackwardActionName;
     case MediaSessionAction::SEEK_FORWARD:
-      return EventTypeNames::seekforward;
+      return seekForwardActionName;
     default:
       NOTREACHED();
   }
   return WTF::emptyAtom;
 }
 
-WTF::Optional<MediaSessionAction> eventNameToMojomAction(
-    const AtomicString& eventName) {
-  if (EventTypeNames::play == eventName)
+WTF::Optional<MediaSessionAction> actionNameToMojomAction(
+    const String& actionName) {
+  if ("play" == actionName)
     return MediaSessionAction::PLAY;
-  if (EventTypeNames::pause == eventName)
+  if ("pause" == actionName)
     return MediaSessionAction::PAUSE;
-  if (EventTypeNames::previoustrack == eventName)
+  if ("previoustrack" == actionName)
     return MediaSessionAction::PREVIOUS_TRACK;
-  if (EventTypeNames::nexttrack == eventName)
+  if ("nexttrack" == actionName)
     return MediaSessionAction::NEXT_TRACK;
-  if (EventTypeNames::seekbackward == eventName)
+  if ("seekbackward" == actionName)
     return MediaSessionAction::SEEK_BACKWARD;
-  if (EventTypeNames::seekforward == eventName)
+  if ("seekforward" == actionName)
     return MediaSessionAction::SEEK_FORWARD;
 
   NOTREACHED();
@@ -140,12 +149,43 @@ void MediaSession::onMetadataChanged() {
       m_metadata, getExecutionContext()));
 }
 
-const WTF::AtomicString& MediaSession::interfaceName() const {
-  return EventTargetNames::MediaSession;
+void MediaSession::setActionHandler(const String& action,
+                                    MediaSessionActionHandler* handler) {
+  if (handler) {
+    auto addResult = m_actionHandlers.set(
+        action, TraceWrapperMember<MediaSessionActionHandler>(this, handler));
+
+    if (!addResult.isNewEntry)
+      return;
+
+    notifyActionChange(action, ActionChangeType::ActionEnabled);
+  } else {
+    if (m_actionHandlers.find(action) == m_actionHandlers.end())
+      return;
+
+    m_actionHandlers.remove(action);
+
+    notifyActionChange(action, ActionChangeType::ActionDisabled);
+  }
 }
 
-ExecutionContext* MediaSession::getExecutionContext() const {
-  return ContextClient::getExecutionContext();
+void MediaSession::notifyActionChange(const String& action,
+                                      ActionChangeType type) {
+  mojom::blink::MediaSessionService* service = getService();
+  if (!service)
+    return;
+
+  auto mojomAction = actionNameToMojomAction(action);
+  DCHECK(mojomAction.has_value());
+
+  switch (type) {
+    case ActionChangeType::ActionEnabled:
+      service->EnableAction(mojomAction.value());
+      break;
+    case ActionChangeType::ActionDisabled:
+      service->DisableAction(mojomAction.value());
+      break;
+  }
 }
 
 mojom::blink::MediaSessionService* MediaSession::getService() {
@@ -171,43 +211,36 @@ mojom::blink::MediaSessionService* MediaSession::getService() {
   return m_service.get();
 }
 
-bool MediaSession::addEventListenerInternal(
-    const AtomicString& eventType,
-    EventListener* listener,
-    const AddEventListenerOptionsResolved& options) {
-  if (mojom::blink::MediaSessionService* service = getService()) {
-    auto mojomAction = eventNameToMojomAction(eventType);
-    DCHECK(mojomAction.has_value());
-    service->EnableAction(mojomAction.value());
-  }
-  return EventTarget::addEventListenerInternal(eventType, listener, options);
-}
-
-bool MediaSession::removeEventListenerInternal(
-    const AtomicString& eventType,
-    const EventListener* listener,
-    const EventListenerOptions& options) {
-  if (mojom::blink::MediaSessionService* service = getService()) {
-    auto mojomAction = eventNameToMojomAction(eventType);
-    DCHECK(mojomAction.has_value());
-    service->DisableAction(mojomAction.value());
-  }
-  return EventTarget::removeEventListenerInternal(eventType, listener, options);
-}
-
 void MediaSession::DidReceiveAction(
     blink::mojom::blink::MediaSessionAction action) {
   DCHECK(getExecutionContext()->isDocument());
   Document* document = toDocument(getExecutionContext());
   UserGestureIndicator gestureIndicator(
       DocumentUserGestureToken::create(document));
-  dispatchEvent(Event::create(mojomActionToEventName(action)));
+
+  auto iter = m_actionHandlers.find(mojomActionToActionName(action));
+  if (iter == m_actionHandlers.end())
+    return;
+
+  iter->value->call(this);
+}
+
+void MediaSession::setV8ReferencesForHandlers(
+    v8::Isolate* isolate,
+    const v8::Persistent<v8::Object>& wrapper) {
+  for (auto handler : m_actionHandlers.values())
+    handler->setWrapperReference(isolate, wrapper);
 }
 
 DEFINE_TRACE(MediaSession) {
   visitor->trace(m_metadata);
-  EventTargetWithInlineData::trace(visitor);
+  visitor->trace(m_actionHandlers);
   ContextClient::trace(visitor);
 }
 
+DEFINE_TRACE_WRAPPERS(MediaSession) {
+  for (auto handler : m_actionHandlers.values())
+    visitor->traceWrappers(handler);
+}
+
 }  // namespace blink

third_party/WebKit/Source/modules/mediasession/MediaSession.h

@@ -6,22 +6,25 @@
 #define MediaSession_h
 
 #include "bindings/core/v8/ScriptWrappable.h"
+#include "bindings/core/v8/TraceWrapperMember.h"
 #include "core/dom/ContextLifecycleObserver.h"
-#include "core/events/EventTarget.h"
 #include "modules/ModulesExport.h"
 #include "mojo/public/cpp/bindings/binding.h"
 #include "platform/heap/Handle.h"
 #include "public/platform/modules/mediasession/media_session.mojom-blink.h"
+#include "wtf/text/WTFString.h"
 #include <memory>
 
 namespace blink {
 
 class ExecutionContext;
 class MediaMetadata;
+class MediaSessionActionHandler;
 
 class MODULES_EXPORT MediaSession final
-    : public EventTargetWithInlineData,
+    : public GarbageCollectedFinalized<MediaSession>,
       public ContextClient,
+      public ScriptWrappable,
       blink::mojom::blink::MediaSessionClient {
   USING_GARBAGE_COLLECTED_MIXIN(MediaSession);
   DEFINE_WRAPPERTYPEINFO();
@@ -38,45 +41,41 @@ class MODULES_EXPORT MediaSession final
   void setMetadata(MediaMetadata*);
   MediaMetadata* metadata() const;
 
-  // EventTarget implementation.
-  const WTF::AtomicString& interfaceName() const override;
-  ExecutionContext* getExecutionContext() const override;
+  void setActionHandler(const String& action, MediaSessionActionHandler*);
 
   // Called by the MediaMetadata owned by |this| when it has updates. Also used
   // internally when a new MediaMetadata object is set.
   void onMetadataChanged();
 
-  DEFINE_ATTRIBUTE_EVENT_LISTENER(play);
-  DEFINE_ATTRIBUTE_EVENT_LISTENER(pause);
-  DEFINE_ATTRIBUTE_EVENT_LISTENER(previoustrack);
-  DEFINE_ATTRIBUTE_EVENT_LISTENER(nexttrack);
-  DEFINE_ATTRIBUTE_EVENT_LISTENER(seekforward);
-  DEFINE_ATTRIBUTE_EVENT_LISTENER(seekbackward);
-
   DECLARE_VIRTUAL_TRACE();
+  DECLARE_VIRTUAL_TRACE_WRAPPERS();
 
  private:
+  friend class V8MediaSession;
   friend class MediaSessionTest;
 
+  enum class ActionChangeType {
+    ActionEnabled,
+    ActionDisabled,
+  };
+
   explicit MediaSession(ExecutionContext*);
 
-  // EventTarget overrides
-  bool addEventListenerInternal(
-      const AtomicString& eventType,
-      EventListener*,
-      const AddEventListenerOptionsResolved&) override;
-  bool removeEventListenerInternal(const AtomicString& eventType,
-                                   const EventListener*,
-                                   const EventListenerOptions&) override;
+  void notifyActionChange(const String& action, ActionChangeType);
 
   // blink::mojom::blink::MediaSessionClient implementation.
   void DidReceiveAction(blink::mojom::blink::MediaSessionAction) override;
 
+  void setV8ReferencesForHandlers(v8::Isolate*,
+                                  const v8::Persistent<v8::Object>& wrapper);
+
   // Returns null when the ExecutionContext is not document.
   mojom::blink::MediaSessionService* getService();
 
   mojom::blink::MediaSessionPlaybackState m_playbackState;
   Member<MediaMetadata> m_metadata;
+  HeapHashMap<String, TraceWrapperMember<MediaSessionActionHandler>>
+      m_actionHandlers;
   mojom::blink::MediaSessionServicePtr m_service;
   mojo::Binding<blink::mojom::blink::MediaSessionClient> m_clientBinding;
 };

third_party/WebKit/Source/modules/mediasession/MediaSession.idl

@@ -12,17 +12,24 @@ enum MediaSessionPlaybackState {
 
 // https://wicg.github.io/mediasession/#the-mediasession-interface
 
+enum MediaSessionAction {
+  "play",
+  "pause",
+  "previoustrack",
+  "nexttrack",
+  "seekbackward",
+  "seekforward"
+};
+
+callback MediaSessionActionHandler = void ();
+
 [
+    Custom=VisitDOMWrapper,
     RuntimeEnabled=MediaSession,
 ] interface MediaSession : EventTarget {
     attribute MediaMetadata? metadata;
-
     attribute MediaSessionPlaybackState playbackState;
 
-    attribute EventHandler onplay;
-    attribute EventHandler onpause;
-    attribute EventHandler onprevioustrack;
-    attribute EventHandler onnexttrack;
-    attribute EventHandler onseekforward;
-    attribute EventHandler onseekbackward;
+    void setActionHandler(MediaSessionAction action,
+                          MediaSessionActionHandler? handler);
 };

third_party/WebKit/Source/modules/mediasession/NavigatorMediaSession.cpp

@@ -4,7 +4,7 @@
 
 #include "modules/mediasession/NavigatorMediaSession.h"
 
-#include "bindings/core/v8/ExceptionStatePlaceholder.h"
+#include "bindings/core/v8/ScriptState.h"
 #include "modules/mediasession/MediaSession.h"
 #include "platform/Supplementable.h"
 

third_party/WebKit/Source/modules/mediasession/NavigatorMediaSession.h

@@ -12,6 +12,7 @@
 namespace blink {
 
 class Navigator;
+class ScriptState;
 
 // Provides MediaSession as a supplement of Navigator as an attribute.
 class NavigatorMediaSession final