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

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

Index: third_party/WebKit/Source/modules/webaudio/BaseAudioContext.h
diff --git a/third_party/WebKit/Source/modules/webaudio/BaseAudioContext.h b/third_party/WebKit/Source/modules/webaudio/BaseAudioContext.h
index aea84aa2697dd34f91c933bb361d052006f7fdb3..d5867dddbafc919eb571879aefda7201ed64be3d 100644
--- a/third_party/WebKit/Source/modules/webaudio/BaseAudioContext.h
+++ b/third_party/WebKit/Source/modules/webaudio/BaseAudioContext.h
@@ -244,7 +244,9 @@ public:
 
     DEFINE_ATTRIBUTE_EVENT_LISTENER(statechange);
 
+    // Start the AudioContext. `isAllowedToStart()` MUST be called before.
     void startRendering();
+
     void notifyStateChange();
 
     // A context is considered closed if:
@@ -259,11 +261,6 @@ public:
     // if necessary.
     PeriodicWave* periodicWave(int type);
 
-    // Check whether the AudioContext requires a user gesture and whether the
-    // current stack is processing user gesture and record these information in
-    // a histogram.
-    void recordUserGestureState();
-
 protected:
     explicit BaseAudioContext(Document*);
     BaseAudioContext(Document*, unsigned numberOfChannels, size_t numberOfFrames, float sampleRate);
@@ -293,6 +290,13 @@ protected:
 
     void rejectPendingDecodeAudioDataResolvers();
 
+    // If any, unlock user gesture requirements if a user gesture is being
+    // processed.
+    void maybeUnlockUserGesture();
+
+    // Returns whether the AudioContext is allowed to start rendering.
+    bool isAllowedToStart() const;
+
 private:
     bool m_isCleared;
     void clear();