Measure whether muted videos that started playing with play() become visible at some point

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

+// 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.
+
+#ifndef AutoplayUmaHelper_h
+#define AutoplayUmaHelper_h
+
+#include "core/events/EventListener.h"
+#include "platform/heap/Handle.h"
+
+namespace blink {
+
+// These values are used for histograms. Do not reorder.
+enum class AutoplaySource {
+    // Autoplay comes from HTMLMediaElement `autoplay` attribute.
+    Attribute = 0,
+    // Autoplay comes from `play()` method.
+    Method = 1,
+    // This enum value must be last.
+    NumberOfSources = 2,
+};
+
+// These values are used for histograms. Do not reorder.
+enum class AutoplayUnmuteActionStatus {
+    Failure = 0,
+    Success = 1,
+    NumberOfStatus = 2,
+};

[mlamouri (slow - plz ping), 2016/07/07 12:45:47]

BTW, I think you can fwd declare these enums here and define them in the cpp
file.

[Zhiqiang Zhang (Slow), 2016/07/08 18:16:49]

These enums are referenced in HTMLMediaElement, so I think not.

+
+class ElementVisibilityObserver;
+class HTMLMediaElement;
+
+class AutoplayUmaHelper final : public EventListener {
+public:
+    static AutoplayUmaHelper* create(HTMLMediaElement*);
+
+    ~AutoplayUmaHelper();
+
+    bool operator==(const EventListener&) const override;
+
+    void onAutoplayInitiated(AutoplaySource);
+    void onElementDestroyed();
+
+    void recordAutoplayUnmuteStatus(AutoplayUnmuteActionStatus);
+
+    void onVisibilityChangedForVideoMutedPlayMethod(bool isVisible);
+
+    DECLARE_VIRTUAL_TRACE();
+
+private:
+    explicit AutoplayUmaHelper(HTMLMediaElement*);
+
+    void handleEvent(ExecutionContext*, Event*) override;
+
+    void handlePlayingEvent();
+
+    // The autoplay source. Use AutoplaySource::NumberOfSources for invalid source.
+    AutoplaySource m_source;
+    // The media element this UMA helper is attached to. |m_element| owns |this|.
+    WeakMember<HTMLMediaElement> m_element;
+    // The observer is used to observe whether a muted video autoplaying by play() method become visible at some point.
+    Member<ElementVisibilityObserver> m_videoMutedPlayMethodVisibilityObserver;
+};
+
+} // namespace blink
+
+#endif // AutoplayUmaHelper_h