Bug 1112761 part 1. Replace Pref="media.mediasource.enabled" annotations in IDL with calls to a function which will end up doing something a bit more interesting. r=kinetik

dom/media/mediasource/MediaSource.cpp

@@ -306,6 +306,12 @@ MediaSource::IsTypeSupported(const GlobalObject&, const nsAString& aType)
   return NS_SUCCEEDED(rv);
 }
 
+/* static */ bool
+MediaSource::Enabled(JSContext* cx, JSObject* aGlobal)
+{
+  return Preferences::GetBool("media.mediasource.enabled");
+}
+
 bool
 MediaSource::Attach(MediaSourceDecoder* aDecoder)
 {

dom/media/mediasource/MediaSource.h

@@ -60,6 +60,8 @@ public:
 
   void EndOfStream(const Optional<MediaSourceEndOfStreamError>& aError, ErrorResult& aRv);
   static bool IsTypeSupported(const GlobalObject&, const nsAString& aType);
+
+  static bool Enabled(JSContext* cx, JSObject* aGlobal);
   /** End WebIDL Methods. */
 
   NS_DECL_ISUPPORTS_INHERITED

dom/webidl/HTMLVideoElement.webidl

@@ -48,6 +48,6 @@ partial interface HTMLVideoElement {
 
 // https://dvcs.w3.org/hg/html-media/raw-file/default/media-source/media-source.html#idl-def-HTMLVideoElement
 partial interface HTMLVideoElement {
-  [Pref="media.mediasource.enabled", NewObject]
+  [Func="mozilla::dom::MediaSource::Enabled", NewObject]
   VideoPlaybackQuality getVideoPlaybackQuality();
 };

dom/webidl/MediaSource.webidl

@@ -21,7 +21,7 @@ enum MediaSourceEndOfStreamError {
   "decode"
 };
 
-[Constructor, Pref="media.mediasource.enabled"]
+[Constructor, Func="mozilla::dom::MediaSource::Enabled"]
 interface MediaSource : EventTarget {
   readonly attribute SourceBufferList sourceBuffers;
   readonly attribute SourceBufferList activeSourceBuffers;

dom/webidl/SourceBuffer.webidl

@@ -15,7 +15,7 @@ enum SourceBufferAppendMode {
     "sequence"
 };
 
-[Pref="media.mediasource.enabled"]
+[Func="mozilla::dom::MediaSource::Enabled"]
 interface SourceBuffer : EventTarget {
   [SetterThrows]
   attribute SourceBufferAppendMode mode;

dom/webidl/SourceBufferList.webidl

@@ -10,7 +10,7 @@
  * liability, trademark and document use rules apply.
  */
 
-[Pref="media.mediasource.enabled"]
+[Func="mozilla::dom::MediaSource::Enabled"]
 interface SourceBufferList : EventTarget {
   readonly attribute unsigned long length;
   getter SourceBuffer (unsigned long index);

dom/webidl/VideoPlaybackQuality.webidl

@@ -10,7 +10,7 @@
  * liability, trademark and document use rules apply.
  */
 
-[Pref="media.mediasource.enabled"]
+[Func="mozilla::dom::MediaSource::Enabled"]
 interface VideoPlaybackQuality {
   readonly attribute DOMHighResTimeStamp creationTime;
   readonly attribute unsigned long totalVideoFrames;