Record whether and why the media default controls are being shown.

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

 /*
  * Copyright (C) 2007, 2008, 2009, 2010, 2011, 2012, 2013 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 93 matching lines @@
 using namespace HTMLNames;
 
 using WeakMediaElementSet = WillBeHeapHashSet<RawPtrWillBeWeakMember<HTMLMediaElement>>;
 using DocumentElementSetMap = WillBeHeapHashMap<RawPtrWillBeWeakMember<Document>, WeakMediaElementSet>;
 
 namespace {
 
 // URL protocol used to signal that the media source API is being used.
 const char mediaSourceBlobProtocol[] = "blob";
 
+enum MediaControlsShow {
+    MediaControlsShowAttribute = 0,
+    MediaControlsShowFullscreen,
+    MediaControlsShowNoScript,
+    MediaControlsShowNone,

[philipj_slow, 2016/02/19 04:05:43]

Maybe MediaControlsNotShown?

[mlamouri (slow - plz ping), 2016/02/23 18:42:13]

Done.

+    MediaControlsShowMax

[philipj_slow, 2016/02/19 04:05:43]

AutoplayExperimentHelper.h has NumberOfAutoplayMetrics, unless that's a weird
exception being consistent with that would be nice. UseCounter's
NumberOfFeatures is also familiar to me.

[mlamouri (slow - plz ping), 2016/02/23 18:42:13]

Yes, it is a weird exception, see:
https://code.google.com/p/chromium/codesearch#search/&q=%22DEFINE_STATIC_LOCA...

[philipj_slow, 2016/02/24 09:54:33]

OK, there's a bit of both, and some *Count as well.

+};
+
 #if !LOG_DISABLED
 String urlForLoggingMedia(const KURL& url)
 {
     static const unsigned maximumURLLengthForLogging = 128;
 
     if (url.string().length() < maximumURLLengthForLogging)
         return url.string();
     return url.string().substring(0, maximumURLLengthForLogging) + "...";
 }
 
@@ skipping 1952 matching lines @@
 }
 
 void HTMLMediaElement::setLoop(bool b)
 {
     WTF_LOG(Media, "HTMLMediaElement::setLoop(%p, %s)", this, boolString(b));
     setBooleanAttribute(loopAttr, b);
 }
 
 bool HTMLMediaElement::shouldShowControls() const
 {
-    LocalFrame* frame = document().frame();
-
-    // always show controls when scripting is disabled
-    if (frame && !frame->script().canExecuteScripts(NotAboutToExecuteScript))
-        return true;
-
-    // Always show controls when in full screen mode.
-    if (isFullscreen())
-        return true;
-
-    return fastHasAttribute(controlsAttr);
+    return shouldShowControlsInternal(false);
 }
 
 double HTMLMediaElement::volume() const
 {
     return m_volume;
 }
 
 void HTMLMediaElement::setVolume(double vol, ExceptionState& exceptionState)
 {
     WTF_LOG(Media, "HTMLMediaElement::setVolume(%p, %f)", this, vol);
@@ skipping 1239 matching lines @@
 void HTMLMediaElement::configureMediaControls()
 {
     if (!inDocument()) {
         if (mediaControls())
             mediaControls()->hide();
         return;
     }
 
     ensureMediaControls();
     mediaControls()->reset();
-    if (shouldShowControls())
+
+    if (shouldShowControlsInternal(true))
         mediaControls()->show();
     else
         mediaControls()->hide();
 }
 
 CueTimeline& HTMLMediaElement::cueTimeline()
 {
     if (!m_cueTimeline)
         m_cueTimeline = adoptPtrWillBeNoop(new CueTimeline(*this));
     return *m_cueTimeline;
@@ skipping 201 matching lines @@
 {
     m_autoplayHelper.updatePositionNotificationRegistration();
 }
 
 // TODO(liberato): remove once autoplay gesture override experiment concludes.
 void HTMLMediaElement::triggerAutoplayViewportCheckForTesting()
 {
     m_autoplayHelper.triggerAutoplayViewportCheckForTesting();
 }
 
+bool HTMLMediaElement::shouldShowControlsInternal(bool record) const
+{
+    DEFINE_STATIC_LOCAL(EnumerationHistogram, showControlsHistogram, ("Media.Controls.Show", MediaControlsShowMax));
+
+    // These checks are in order of conditions superseeding each other, which

[philipj_slow, 2016/02/19 04:05:43]

Well, this would be true of any order where all "return true" are before the
"return false". The actual reason for the order is the expected frequency of
each case, with the most frequent cause first.

[mlamouri (slow - plz ping), 2016/02/23 18:42:13]

I understand what you mean. I guess my comment is confusing. I simply removed
it.

+    // also matches speed. In other words, a media element with a controls
+    // attribute, will always have controls, regardless of the other conditions.
+    // Same for an element in fullscreen. That means that recorded metrics will
+    // only show the superseeding reason of the controls showing.
+
+    if (fastHasAttribute(controlsAttr)) {
+        if (record)
+            showControlsHistogram.count(MediaControlsShowAttribute);
+        return true;
+    }
+
+    if (isFullscreen()) {
+        if (record)
+            showControlsHistogram.count(MediaControlsShowFullscreen);
+        return true;
+    }
+
+    LocalFrame* frame = document().frame();
+    if (frame && !frame->script().canExecuteScripts(NotAboutToExecuteScript)) {
+        if (record)
+            showControlsHistogram.count(MediaControlsShowNoScript);
+        return true;
+    }
+
+    showControlsHistogram.count(MediaControlsShowNone);
+    return false;
+}
+
 void HTMLMediaElement::clearWeakMembers(Visitor* visitor)
 {
     if (!Heap::isHeapObjectAlive(m_audioSourceNode))
         audioSourceProvider().setClient(nullptr);
 }
 
 void HTMLMediaElement::AudioSourceProviderImpl::wrap(WebAudioSourceProvider* provider)
 {
     MutexLocker locker(provideInputLock);
 
@@ skipping 47 matching lines @@
 {
     visitor->trace(m_client);
 }
 
 DEFINE_TRACE(HTMLMediaElement::AudioSourceProviderImpl)
 {
     visitor->trace(m_client);
 }
 
 } // namespace blink