Warn about Web Audio without user gesture on Android no longer allowed on cross origin iframes.

third_party/WebKit/Source/modules/webaudio/BaseAudioContext.cpp

 /*
  * Copyright (C) 2010, Google 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 15 matching lines @@
 
 #include "bindings/core/v8/Dictionary.h"
 #include "bindings/core/v8/ExceptionMessages.h"
 #include "bindings/core/v8/ExceptionState.h"
 #include "bindings/core/v8/ScriptPromiseResolver.h"
 #include "bindings/core/v8/ScriptState.h"
 #include "core/dom/DOMException.h"
 #include "core/dom/Document.h"
 #include "core/dom/ExceptionCode.h"
 #include "core/dom/ExecutionContextTask.h"
+#include "core/frame/Deprecation.h"
 #include "core/frame/Settings.h"
 #include "core/html/HTMLMediaElement.h"
 #include "modules/mediastream/MediaStream.h"
 #include "modules/webaudio/AnalyserNode.h"
 #include "modules/webaudio/AudioBuffer.h"
 #include "modules/webaudio/AudioBufferCallback.h"
 #include "modules/webaudio/AudioBufferSourceNode.h"
 #include "modules/webaudio/AudioContext.h"
 #include "modules/webaudio/AudioListener.h"
 #include "modules/webaudio/AudioNodeInput.h"
@@ skipping 500 matching lines @@
 {
     DEFINE_STATIC_LOCAL(EnumerationHistogram, userGestureHistogram, ("WebAudio.UserGesture", UserGestureRecordMax));
 
     if (!m_userGestureRequired) {
         if (UserGestureIndicator::processingUserGesture())
             userGestureHistogram.count(UserGestureNotRequiredAndAvailable);
         else
             userGestureHistogram.count(UserGestureNotRequiredAndNotAvailable);
         return;
     }
+
+    DCHECK(m_userGestureRequired);

[Raymond Toy, 2016/09/06 15:32:32]

Don't quite understand why m_userGestureRequired has to be true here. In line
550, m_userGestureRequired is tested (for false), but the body doesn't ever seem
to set it to anything and doesn't always return, so m_userGestureRequired could
be false at line 558.

What am I missing?

[mlamouri (slow - plz ping), 2016/09/06 15:43:00]

It always return :)

I added the DCHECK() because I was a bit surprised by this code (that I wrote
myself).

[Raymond Toy, 2016/09/06 15:44:56]

Oh, duh! I read the return as inside the else.

lgtm for the webaudio parts.

     if (!UserGestureIndicator::processingUserGesture()) {
         userGestureHistogram.count(UserGestureRequiredAndNotAvailable);
+
+        Document* document = toDocument(getExecutionContext());
+        if (document)
+            Deprecation::countDeprecationCrossOriginIframe(*document, UseCounter::WebAudioAutoplayCrossOriginIframe);
+
         return;
     }
     userGestureHistogram.count(UserGestureRequiredAndAvailable);
     m_userGestureRequired = false;
 }
 
 String BaseAudioContext::state() const
 {
     // These strings had better match the strings for AudioContextState in AudioContext.idl.
     switch (m_contextState) {
@@ skipping 263 matching lines @@
 
 SecurityOrigin* BaseAudioContext::getSecurityOrigin() const
 {
     if (getExecutionContext())
         return getExecutionContext()->getSecurityOrigin();
 
     return nullptr;
 }
 
 } // namespace blink