Notify on console when play fails

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 41 matching lines @@
 #include "core/html/shadow/MediaControls.h"
 #include "core/html/track/AudioTrack.h"
 #include "core/html/track/AudioTrackList.h"
 #include "core/html/track/AutomaticTrackSelection.h"
 #include "core/html/track/CueTimeline.h"
 #include "core/html/track/InbandTextTrack.h"
 #include "core/html/track/TextTrackContainer.h"
 #include "core/html/track/TextTrackList.h"
 #include "core/html/track/VideoTrack.h"
 #include "core/html/track/VideoTrackList.h"
+#include "core/inspector/ConsoleMessage.h"
 #include "core/layout/LayoutVideo.h"
 #include "core/layout/LayoutView.h"
 #include "core/layout/compositing/DeprecatedPaintLayerCompositor.h"
 #include "core/loader/FrameLoader.h"
 #include "platform/ContentType.h"
 #include "platform/Logging.h"
 #include "platform/MIMETypeFromURL.h"
 #include "platform/MIMETypeRegistry.h"
 #include "platform/RuntimeEnabledFeatures.h"
 #include "platform/UserGestureIndicator.h"
@@ skipping 1835 matching lines @@
 {
     return autoplay() ? MediaPlayer::Auto : m_preload;
 }
 
 void HTMLMediaElement::play()
 {
     WTF_LOG(Media, "HTMLMediaElement::play(%p)", this);
 
     if (!UserGestureIndicator::processingUserGesture()) {
         autoplayMediaEncountered();
-        if (m_userGestureRequiredForPlay)
+        if (m_userGestureRequiredForPlay) {
+            String message = ExceptionMessages::failedToExecute("play", "MediaElement", "API can only be initiated by a user gesture.");

[philipj_slow, 2015/06/04 08:16:38]

This should say "HTMLMediaElement", there's no interface called only
"MediaElement".

+            document().executionContext()->addConsoleMessage(ConsoleMessage::create(JSMessageSource, WarningMessageLevel, message));
             return;
+        }
     } else if (m_userGestureRequiredForPlay) {
         if (m_autoplayMediaCounted)
             recordAutoplayMetric(AutoplayManualStart);
         m_userGestureRequiredForPlay = false;
     }
 
     playInternal();
 }
 
 void HTMLMediaElement::playInternal()
@@ skipping 1731 matching lines @@
 
 #if ENABLE(WEB_AUDIO)
 void HTMLMediaElement::clearWeakMembers(Visitor* visitor)
 {
     if (!Heap::isHeapObjectAlive(m_audioSourceNode) && audioSourceProvider())
         audioSourceProvider()->setClient(nullptr);
 }
 #endif
 
 }