Simplify ElementVisibilityObserver implementation.

third_party/WebKit/Source/core/html/HTMLMediaElement.h

Index: third_party/WebKit/Source/core/html/HTMLMediaElement.h
diff --git a/third_party/WebKit/Source/core/html/HTMLMediaElement.h b/third_party/WebKit/Source/core/html/HTMLMediaElement.h
index 2505616af94ea7ca993426a45f40c022475b1f5b..72d6c1d066549d9349c4c8f913fde74ca1bdc3d7 100644
--- a/third_party/WebKit/Source/core/html/HTMLMediaElement.h
+++ b/third_party/WebKit/Source/core/html/HTMLMediaElement.h
@@ -30,6 +30,7 @@
 #include "bindings/core/v8/ScriptPromise.h"
 #include "core/CoreExport.h"
 #include "core/dom/ActiveDOMObject.h"
+#include "core/dom/ElementVisibilityObserver.h"
 #include "core/dom/ExceptionCode.h"
 #include "core/events/GenericEventQueue.h"
 #include "core/html/AutoplayExperimentHelper.h"
@@ -70,7 +71,7 @@ class WebInbandTextTrack;
 class WebLayer;
 class WebRemotePlaybackClient;
 
-class CORE_EXPORT HTMLMediaElement : public HTMLElement, public Supplementable<HTMLMediaElement>, public ActiveScriptWrappable, public ActiveDOMObject, private WebMediaPlayerClient {
+class CORE_EXPORT HTMLMediaElement : public HTMLElement, public Supplementable<HTMLMediaElement>, public ActiveScriptWrappable, public ActiveDOMObject, private WebMediaPlayerClient, private ElementVisibilityObserver::Client {
     DEFINE_WRAPPERTYPEINFO();
     USING_GARBAGE_COLLECTED_MIXIN(HTMLMediaElement);
     USING_PRE_FINALIZER(HTMLMediaElement, dispose);
@@ -502,7 +503,9 @@ private:
     void recordAutoplaySourceMetric(int source);
     void recordAutoplayUnmuteStatus(AutoplayUnmuteActionStatus);
 
-    void onVisibilityChangedForAutoplay(bool isVisible);
+    // ElementVisibilityObserver::Client implementation
+    void onVisibilityChanged(bool isVisible) override;
+    ExecutionContext* getElementVisibilityExecutionContext() const override { return getExecutionContext(); }
 
     UnthrottledTimer<HTMLMediaElement> m_loadTimer;
     UnthrottledTimer<HTMLMediaElement> m_progressEventTimer;