import changes from `dev' branch of rmottola/Arctic-Fox:

- Bug 1184429: P1. Don't dispatch NotifyDataArrived if previously dispatched with same range. r=jwwang (23c800ae85)
- partial of Bug 1184429: P2. MediaResource::SilentReadAt to read from cache first. r=jwwang (8cee1efb46)
- Bug 1173463 - Add MediaResource::GetContentURL(). r=cpearce (a204aeff0a)
- Bug 1142455 - Tweak MediaCache parameters. r=roc (a3ded56f74)

dom/media/MediaData.h

@@ -432,6 +432,8 @@ private:
   // MediaByteBuffer is a ref counted infallible TArray.
 class MediaByteBuffer : public nsTArray<uint8_t> {
   NS_INLINE_DECL_THREADSAFE_REFCOUNTING(MediaByteBuffer);
+  MediaByteBuffer() = default;
+  explicit MediaByteBuffer(size_t aCapacity) : nsTArray<uint8_t>(aCapacity) {}
 
 private:
   ~MediaByteBuffer() {}

dom/media/MediaDecoderReader.cpp

@@ -192,6 +192,8 @@ MediaDecoderReader::ThrottledNotifyDataArrived(const Interval<int64_t>& aInterva
 
   if (mThrottledInterval.isNothing()) {
     mThrottledInterval.emplace(aInterval);
+  } else if (mThrottledInterval.ref().Contains(aInterval)) {
+    return;
   } else if (!mThrottledInterval.ref().Contiguous(aInterval)) {
     DoThrottledNotify();
     mThrottledInterval.emplace(aInterval);

dom/media/MediaResource.h

@@ -25,7 +25,11 @@
 // For HTTP seeking, if number of bytes needing to be
 // seeked forward is less than this value then a read is
 // done rather than a byte range request.
-static const int64_t SEEK_VS_READ_THRESHOLD = 32*1024;
+//
+// If we assume a 100Mbit connection, and assume reissuing an HTTP seek causes
+// a delay of 200ms, then in that 200ms we could have simply read ahead 2MB. So
+// setting SEEK_VS_READ_THRESHOLD to 1MB sounds reasonable.
+static const int64_t SEEK_VS_READ_THRESHOLD = 1 * 1024 * 1024;
 
 static const uint32_t HTTP_REQUESTED_RANGE_NOT_SATISFIABLE_CODE = 416;
 
@@ -435,6 +439,8 @@ public:
     return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
   }
 
+  const nsCString& GetContentURL() const { return EmptyCString(); }
+
 protected:
   virtual ~MediaResource() {};
 
@@ -467,6 +473,12 @@ public:
     return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
   }
 
+  // Returns the url of the resource. Safe to call from any thread?
+  const nsCString& GetContentURL() const
+  {
+    return mContentURL;
+  }
+
 protected:
   BaseMediaResource(MediaDecoder* aDecoder,
                     nsIChannel* aChannel,
@@ -480,6 +492,7 @@ protected:
   {
     MOZ_COUNT_CTOR(BaseMediaResource);
     NS_ASSERTION(!mContentType.IsEmpty(), "Must know content type");
+    mURI->GetSpec(mContentURL);
   }
   virtual ~BaseMediaResource()
   {
@@ -518,6 +531,9 @@ protected:
   // is safe.
   const nsAutoCString mContentType;
 
+  // Copy of the url of the channel resource.
+  nsAutoCString mContentURL;
+
   // True if SetLoadInBackground() has been called with
   // aLoadInBackground = true, i.e. when the document load event is not
   // blocked by this resource, and all channel loads will be in the