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..a5709587175969c02759dc561e83245fcddae52c
--- /dev/null
+++ b/third_party/WebKit/Source/core/html/AutoplayUmaHelper.h
@@ -0,0 +1,51 @@
+// 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 "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,
+};
+
+class HTMLMediaElement;
+
+class AutoplayUmaHelper final : public GarbageCollectedFinalized<AutoplayUmaHelper> {
+
+public:
+
+    static AutoplayUmaHelper* create(HTMLMediaElement* element)
+    {
+        return new AutoplayUmaHelper(element);
+    }
+
+    ~AutoplayUmaHelper();
+
+    void onAutoplayInitiated(AutoplaySource);
+    void onAutoplayStarted();
+    void onElementDestroyed();
+
+    DECLARE_TRACE();
+
+private:
+    explicit AutoplayUmaHelper(HTMLMediaElement*);
+
+    // The autoplay source. Use AutoplaySource::NumberOfSources for invalid source.
+    AutoplaySource m_source;
+    WeakMember<HTMLMediaElement> m_element;
+};
+
+} // namespace blink
+
+#endif // AutoplayUmaHelper_h