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

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

Index: third_party/WebKit/Source/core/html/AutoplayUmaHelper.cpp
diff --git a/third_party/WebKit/Source/core/html/AutoplayUmaHelper.cpp b/third_party/WebKit/Source/core/html/AutoplayUmaHelper.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..97c4df425a0b091a706f57ae794a7d9560d58318
--- /dev/null
+++ b/third_party/WebKit/Source/core/html/AutoplayUmaHelper.cpp
@@ -0,0 +1,112 @@
+// 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.
+
+#include "core/html/AutoplayUmaHelper.h"
+
+#include "core/dom/ElementVisibilityObserver.h"
+#include "core/events/Event.h"
+#include "core/html/HTMLMediaElement.h"
+#include "platform/Histogram.h"
+
+namespace blink {
+
+namespace {
+
+void recordVideoAutoplayMutedPlayMethodBecomesVisibleUma(bool visible)
+{
+    DEFINE_STATIC_LOCAL(BooleanHistogram, histogram, ("Media.Video.Autoplay.Muted.PlayMethod.BecomesVisible"));
+    histogram.count(visible);
+}
+
+} // namespace
+
+AutoplayUmaHelper* AutoplayUmaHelper::create(HTMLMediaElement* element)
+{
+    return new AutoplayUmaHelper(element);
+}
+
+AutoplayUmaHelper::AutoplayUmaHelper(HTMLMediaElement* element)
+    : EventListener(CPPEventListenerType)
+    , m_source(AutoplaySource::NumberOfSources)
+    , m_element(element)
+    , m_videoMutedPlayMethodVisibilityObserver(nullptr) { }
+
+AutoplayUmaHelper::~AutoplayUmaHelper() = default;
+
+bool AutoplayUmaHelper::operator==(const EventListener& other) const
+{
+    return this == &other;
+}
+
+void AutoplayUmaHelper::onAutoplayInitiated(AutoplaySource source)
+{
+    DEFINE_STATIC_LOCAL(EnumerationHistogram, videoHistogram, ("Media.Video.Autoplay", static_cast<int>(AutoplaySource::NumberOfSources)));
+    DEFINE_STATIC_LOCAL(EnumerationHistogram, mutedVideoHistogram, ("Media.Video.Autoplay.Muted", static_cast<int>(AutoplaySource::NumberOfSources)));
+    DEFINE_STATIC_LOCAL(EnumerationHistogram, audioHistogram, ("Media.Audio.Autoplay", static_cast<int>(AutoplaySource::NumberOfSources)));
+
+    m_source = source;
+
+    if (m_element->isHTMLVideoElement()) {
+        videoHistogram.count(static_cast<int>(m_source));
+        if (m_element->muted())
+            mutedVideoHistogram.count(static_cast<int>(m_source));
+    } else {
+        audioHistogram.count(static_cast<int>(m_source));
+    }
+
+    if (m_element->isHTMLVideoElement() && m_element->muted())
+        m_element->addEventListener(EventTypeNames::playing, this, false);

[mlamouri (slow - plz ping), 2016/07/08 17:58:29]

Shouldn't you only add the event listener if source is the method?

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

Oh yes! Nice catch. Fixed.

+}
+
+void AutoplayUmaHelper::onElementDestroyed()
+{
+    if (m_videoMutedPlayMethodVisibilityObserver) {
+        recordVideoAutoplayMutedPlayMethodBecomesVisibleUma(false);
+        m_videoMutedPlayMethodVisibilityObserver->stop();
+        m_videoMutedPlayMethodVisibilityObserver = nullptr;
+    }
+}
+
+void AutoplayUmaHelper::recordAutoplayUnmuteStatus(AutoplayUnmuteActionStatus status)
+{
+    DEFINE_STATIC_LOCAL(EnumerationHistogram, autoplayUnmuteHistogram, ("Media.Video.Autoplay.Muted.UnmuteAction", static_cast<int>(AutoplayUnmuteActionStatus::NumberOfStatus)));
+
+    autoplayUnmuteHistogram.count(static_cast<int>(status));
+}
+
+void AutoplayUmaHelper::onVisibilityChangedForVideoMutedPlayMethod(bool isVisible)
+{
+    if (!isVisible)
+        return;
+
+    recordVideoAutoplayMutedPlayMethodBecomesVisibleUma(true);
+    m_videoMutedPlayMethodVisibilityObserver->stop();
+    m_videoMutedPlayMethodVisibilityObserver = nullptr;
+}
+
+void AutoplayUmaHelper::handleEvent(ExecutionContext* executionContext, Event* event)
+{
+    if (event->type() == EventTypeNames::playing)
+        handlePlayingEvent();

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

What about:
```
DCHECK(event->type() == EventTypeNames::playing);
handlePlayingEvent();
```

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

Done.

+}
+
+void AutoplayUmaHelper::handlePlayingEvent()
+{
+    if (m_source == AutoplaySource::Method && m_element->isHTMLVideoElement() && m_element->muted()) {
+        if (!m_videoMutedPlayMethodVisibilityObserver) {
+            m_videoMutedPlayMethodVisibilityObserver = new ElementVisibilityObserver(m_element, WTF::bind(&AutoplayUmaHelper::onVisibilityChangedForVideoMutedPlayMethod, wrapPersistent(this)));
+            m_videoMutedPlayMethodVisibilityObserver->start();
+        }
+    }
+    m_element->removeEventListener(EventTypeNames::playing, this, false);
+}
+
+DEFINE_TRACE(AutoplayUmaHelper)
+{
+    EventListener::trace(visitor);
+    visitor->trace(m_element);
+    visitor->trace(m_videoMutedPlayMethodVisibilityObserver);
+}
+
+} // namespace blink