Bug 1591620 - part1 : make 'MediaControlKeysEventListener' as a pure interface. r=chunmin

If the web extention also needs to implement its listener, they would definitely not need the current implementation in `KeyPressed()` for controlling media controller. Therefore, we should make `MediaControlKeysEventListener` as a pure interface and let inherited class to define their own `KeyPressed()`.

Differential Revision: https://phabricator.services.mozilla.com/D50686

--HG--
extra : moz-landing-system : lando

dom/media/mediacontrol/MediaControlKeysEvent.cpp

@@ -42,8 +42,7 @@ static const char* ToMediaControlKeysEventStr(MediaControlKeysEvent aKeyEvent) {
              ToMediaControlKeysEventStr(key), ##__VA_ARGS__));    \
   }
 
-void MediaControlKeysEventListener::OnKeyPressed(
-    MediaControlKeysEvent aKeyEvent) {
+void MediaControlKeysHandler::OnKeyPressed(MediaControlKeysEvent aKeyEvent) {
   LOG_KEY("OnKeyPressed '%s'", aKeyEvent);
   switch (aKeyEvent) {
     case MediaControlKeysEvent::ePlayPause: {

dom/media/mediacontrol/MediaControlKeysEvent.h

@@ -14,22 +14,31 @@ namespace dom {
 enum class MediaControlKeysEvent { ePlayPause, ePrev, eNext, eNone };
 
 /**
- * MediaControlKeysEventListener is used to monitor MediaControlKeysEvent, we
- * can add it onto the MediaControlKeysEventSource, and then everytime when
- * the media key events occur, `OnKeyPressed` will be called so that we can do
- * related handling.
+ * MediaControlKeysEventListener is a pure interface, which is used to monitor
+ * MediaControlKeysEvent, we can add it onto the MediaControlKeysEventSource,
+ * and then everytime when the media key events occur, `OnKeyPressed` will be
+ * called so that we can do related handling.
  */
 class MediaControlKeysEventListener {
  public:
   NS_INLINE_DECL_THREADSAFE_REFCOUNTING(MediaControlKeysEventListener);
   MediaControlKeysEventListener() = default;
 
-  virtual void OnKeyPressed(MediaControlKeysEvent aKeyEvent);
+  virtual void OnKeyPressed(MediaControlKeysEvent aKeyEvent) = 0;
 
  protected:
   virtual ~MediaControlKeysEventListener() = default;
 };
 
+/**
+ * MediaControlKeysHandler is used to operate media controller by corresponding
+ * received media control key events.
+ */
+class MediaControlKeysHandler final : public MediaControlKeysEventListener {
+ public:
+  void OnKeyPressed(MediaControlKeysEvent aKeyEvent) override;
+};
+
 /**
  * MediaControlKeysEventSource is a base class which is used to implement
  * transporting media control keys event to all its listeners when media keys

dom/media/mediacontrol/MediaControlKeysManager.cpp

@@ -36,7 +36,7 @@ void MediaControlKeysManager::StartMonitoringControlKeys() {
   }
   CreateEventSource();
   if (mEventSource) {
-    mEventSource->AddListener(new MediaControlKeysEventListener());
+    mEventSource->AddListener(new MediaControlKeysHandler());
   }
 }
 

dom/media/mediacontrol/tests/gtest/TestMediaKeysEvent.cpp

@@ -14,7 +14,7 @@ TEST(MediaControlKeysEvent, TestAddOrRemoveListener)
   ASSERT_TRUE(source->GetListenersNum() == 0);
 
   RefPtr<MediaControlKeysEventListener> listener =
-      new MediaControlKeysEventListener();
+      new MediaControlKeysHandler();
 
   source->AddListener(listener);
   ASSERT_TRUE(source->GetListenersNum() == 1);