From f25bbc3a43b7c4b90c632d6e1e8ace2e1f510caa Mon Sep 17 00:00:00 2001
From: Andrea Marchesini <amarchesini@mozilla.com>
Date: Fri, 10 Jul 2015 17:38:49 +0100
Subject: [PATCH]  Bug 1113086 - AudioChannel policy in Browser API - patch 4 -
 Muted by default, e=alwu

---
 dom/audiochannel/AudioChannelService.cpp | 12 ++++++++++++
 dom/audiochannel/AudioChannelService.h   |  4 +++-
 modules/libpref/init/all.js              |  2 ++
 3 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/dom/audiochannel/AudioChannelService.cpp b/dom/audiochannel/AudioChannelService.cpp
index 253ff3a7f57..30fa3268523 100644
--- a/dom/audiochannel/AudioChannelService.cpp
+++ b/dom/audiochannel/AudioChannelService.cpp
@@ -40,6 +40,9 @@ using namespace mozilla::hal;
 
 namespace {
 
+// If true, any new AudioChannelAgent will be muted when created.
+bool sAudioChannelMutedByDefault = false;
+
 void
 NotifyChannelActive(uint64_t aWindowID, AudioChannel aAudioChannel,
                     bool aActive)
@@ -169,6 +172,9 @@ AudioChannelService::AudioChannelService()
 #endif
     }
   }
+
+  Preferences::AddBoolVarCache(&sAudioChannelMutedByDefault,
+                               "dom.audiochannel.mutedByDefault");
 }
 
 AudioChannelService::~AudioChannelService()
@@ -825,6 +831,12 @@ AudioChannelService::ChildStatusReceived(uint64_t aChildID,
   data->mActiveContentOrNormalChannel = aContentOrNormalChannel;
 }
 
+/* static */ bool
+AudioChannelService::IsAudioChannelMutedByDefault()
+{
+  return sAudioChannelMutedByDefault;
+}
+
 /* static */ PLDHashOperator
 AudioChannelService::NotifyEnumerator(AudioChannelAgent* aAgent,
                                       AudioChannel* aAudioChannel,
diff --git a/dom/audiochannel/AudioChannelService.h b/dom/audiochannel/AudioChannelService.h
index 2b9d10c63d6..1c8345fe162 100644
--- a/dom/audiochannel/AudioChannelService.h
+++ b/dom/audiochannel/AudioChannelService.h
@@ -48,6 +48,8 @@ public:
    */
   static void Shutdown();
 
+  static bool IsAudioChannelMutedByDefault();
+
   /**
    * Any audio channel agent that starts playing should register itself to
    * this service, sharing the AudioChannel.
@@ -146,7 +148,7 @@ private:
   {
     AudioChannelConfig()
       : mVolume(1.0)
-      , mMuted(false)
+      , mMuted(IsAudioChannelMutedByDefault())
       , mNumberOfAgents(0)
     {}
 
diff --git a/modules/libpref/init/all.js b/modules/libpref/init/all.js
index 7171a176fcc..8a0fda5f19c 100644
--- a/modules/libpref/init/all.js
+++ b/modules/libpref/init/all.js
@@ -4957,6 +4957,8 @@ pref("reader.toolbar.vertical", true);
 pref("media.gmp.insecure.allow", false);
 #endif
 
+pref("dom.audiochannel.mutedByDefault", false);
+
 // Use vsync aligned rendering. b2g prefs are in b2g.js.
 // Hardware vsync supported on windows, os x, and b2g.
 // Linux and fennec will use software vsync.