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

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

Index: third_party/WebKit/Source/core/html/AutoplayUmaHelper.h
diff --git a/third_party/WebKit/Source/core/html/AutoplayUmaHelper.h b/third_party/WebKit/Source/core/html/AutoplayUmaHelper.h
new file mode 100644
index 0000000000000000000000000000000000000000..c9245ddf576dd8ee5787163509333274cb323a40
--- /dev/null
+++ b/third_party/WebKit/Source/core/html/AutoplayUmaHelper.h
@@ -0,0 +1,65 @@
+// 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,
+};
+
+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 handlePlayEvent();

[mlamouri (slow - plz ping), 2016/07/07 10:17:53]

handlePlayingEvent. There is an event named 'play' :)

[Zhiqiang Zhang (Slow), 2016/07/07 11:01:10]

Done.

+
+    // The autoplay source. Use AutoplaySource::NumberOfSources for invalid source.
+    AutoplaySource m_source;
+    WeakMember<HTMLMediaElement> m_element;

[mlamouri (slow - plz ping), 2016/07/07 10:17:53]

nit: add comment saying that m_element owns |this|.

[Zhiqiang Zhang (Slow), 2016/07/07 11:01:10]

Done.

+    Member<ElementVisibilityObserver> m_videoMutedPlayMethodVisibilityObserver;

[mlamouri (slow - plz ping), 2016/07/07 10:17:53]

nit: add comment?

[Zhiqiang Zhang (Slow), 2016/07/07 11:01:10]

Done.

+};
+
+} // namespace blink
+
+#endif // AutoplayUmaHelper_h