Web Audio: when media playback requires a user gesture, apply rule to cross origin iframes.

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

 // Copyright 2015 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 "modules/webaudio/AudioContext.h"
 
 #include "bindings/core/v8/ExceptionMessages.h"
 #include "bindings/core/v8/ExceptionState.h"
 #include "bindings/core/v8/ScriptPromiseResolver.h"
 #include "core/dom/DOMException.h"
@@ skipping 46 matching lines @@
                 ExceptionMessages::InclusiveBound));
         return audioContext;
     }
     // This starts the audio thread. The destination node's
     // provideInput() method will now be called repeatedly to render
     // audio.  Each time provideInput() is called, a portion of the
     // audio stream is rendered. Let's call this time period a "render
     // quantum". NOTE: for now AudioContext does not need an explicit
     // startRendering() call from JavaScript.  We may want to consider
     // requiring it for symmetry with OfflineAudioContext.
-    audioContext->startRendering();
+    audioContext->maybeUnlockUserGesture();
+    if (audioContext->isAllowedToStart())
+        audioContext->startRendering();
     ++s_hardwareContextCount;
 #if DEBUG_AUDIONODE_REFERENCES
     fprintf(stderr, "[%16p]: AudioContext::AudioContext(): %u #%u\n",
         audioContext, audioContext->m_contextId, s_hardwareContextCount);
 #endif
 
     DEFINE_STATIC_LOCAL(SparseHistogram, maxChannelCountHistogram,
         ("WebAudio.AudioContext.MaxChannelsAvailable"));
     DEFINE_STATIC_LOCAL(SparseHistogram, sampleRateHistogram,
         ("WebAudio.AudioContext.HardwareSampleRate"));
@@ skipping 51 matching lines @@
     DCHECK(isMainThread());
 
     if (isContextClosed()) {
         return ScriptPromise::rejectWithDOMException(
             scriptState,
             DOMException::create(
                 InvalidAccessError,
                 "cannot resume a closed AudioContext"));
     }
 
-    recordUserGestureState();
-
     ScriptPromiseResolver* resolver = ScriptPromiseResolver::create(scriptState);
     ScriptPromise promise = resolver->promise();
 
     // Restart the destination node to pull on the audio graph.
-    if (destination())
-        startRendering();
+    if (destination()) {
+        maybeUnlockUserGesture();
+        if (isAllowedToStart())
+            startRendering();
+    }
 
     // Save the resolver which will get resolved when the destination node starts pulling on the
     // graph again.
     {
         AutoLocker locker(this);
         m_resumeResolvers.append(resolver);
     }
 
     return promise;
 }
@@ skipping 48 matching lines @@
     DCHECK(destination());
 
     if (contextState() == Running) {
         destination()->audioDestinationHandler().stopRendering();
         setContextState(Suspended);
         deferredTaskHandler().clearHandlersToBeDeleted();
     }
 }
 
 } // namespace blink