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

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

Index: third_party/WebKit/Source/modules/webaudio/BaseAudioContext.cpp
diff --git a/third_party/WebKit/Source/modules/webaudio/BaseAudioContext.cpp b/third_party/WebKit/Source/modules/webaudio/BaseAudioContext.cpp
index 2e72ec0778d2f4d10bedb4b47c8f0f8f00d29de2..2d1e489aa55875d48d66576e229779f104f79649 100644
--- a/third_party/WebKit/Source/modules/webaudio/BaseAudioContext.cpp
+++ b/third_party/WebKit/Source/modules/webaudio/BaseAudioContext.cpp
@@ -33,6 +33,7 @@
 #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"
@@ -553,8 +554,15 @@ void BaseAudioContext::recordUserGestureState()
             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);