From 3c96e8ce58cdfdabe8174700e10fb44145d08982 Mon Sep 17 00:00:00 2001
From: Drew Willcoxon <adw@mozilla.com>
Date: Tue, 28 Jul 2015 12:34:33 -0700
Subject: [PATCH] Bug 1183044 - Properly mute AudioContext when there's an
 attempt to mute it before it has a destination. r=ehsan

---
 dom/base/nsGlobalWindow.cpp         | 7 +++----
 dom/base/nsPIDOMWindow.h            | 2 +-
 dom/media/webaudio/AudioContext.cpp | 7 ++++++-
 3 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/dom/base/nsGlobalWindow.cpp b/dom/base/nsGlobalWindow.cpp
index f0b1e7787bd..98973f7608a 100644
--- a/dom/base/nsGlobalWindow.cpp
+++ b/dom/base/nsGlobalWindow.cpp
@@ -3475,17 +3475,16 @@ nsPIDOMWindow::SetFrameElementInternal(Element* aFrameElement)
   mOuterWindow->SetFrameElementInternal(aFrameElement);
 }
 
-void
+bool
 nsPIDOMWindow::AddAudioContext(AudioContext* aAudioContext)
 {
   MOZ_ASSERT(IsInnerWindow());
 
   mAudioContexts.AppendElement(aAudioContext);
 
+  // Return true if the context should be muted and false if not.
   nsIDocShell* docShell = GetDocShell();
-  if (docShell && !docShell->GetAllowMedia() && !aAudioContext->IsOffline()) {
-    aAudioContext->Mute();
-  }
+  return docShell && !docShell->GetAllowMedia() && !aAudioContext->IsOffline();
 }
 
 void
diff --git a/dom/base/nsPIDOMWindow.h b/dom/base/nsPIDOMWindow.h
index 3e6404e9950..5cda6cba2f0 100644
--- a/dom/base/nsPIDOMWindow.h
+++ b/dom/base/nsPIDOMWindow.h
@@ -718,7 +718,7 @@ public:
                         const nsAString& aPopupWindowFeatures) = 0;
 
   // Inner windows only.
-  void AddAudioContext(mozilla::dom::AudioContext* aAudioContext);
+  bool AddAudioContext(mozilla::dom::AudioContext* aAudioContext);
   void RemoveAudioContext(mozilla::dom::AudioContext* aAudioContext);
   void MuteAudioContexts();
   void UnmuteAudioContexts();
diff --git a/dom/media/webaudio/AudioContext.cpp b/dom/media/webaudio/AudioContext.cpp
index 9d2fdc73caa..b705970dce7 100644
--- a/dom/media/webaudio/AudioContext.cpp
+++ b/dom/media/webaudio/AudioContext.cpp
@@ -101,12 +101,17 @@ AudioContext::AudioContext(nsPIDOMWindow* aWindow,
   , mIsShutDown(false)
   , mCloseCalled(false)
 {
-  aWindow->AddAudioContext(this);
+  bool mute = aWindow->AddAudioContext(this);
 
   // Note: AudioDestinationNode needs an AudioContext that must already be
   // bound to the window.
   mDestination = new AudioDestinationNode(this, aIsOffline, aChannel,
                                           aNumberOfChannels, aLength, aSampleRate);
+
+  // The context can't be muted until it has a destination.
+  if (mute) {
+    Mute();
+  }
 }
 
 void