Bug 1690111 - Use new TypedArray APIs for appending data to a container. r=farre,extension-reviewers,media-playback-reviewers,kmag,alwu,padenot

Depends on D152494

Differential Revision: https://phabricator.services.mozilla.com/D152495

dom/fetch/FetchStreamReader.cpp

@@ -325,21 +325,29 @@ void FetchStreamReader::ChunkSteps(JSContext* aCx, JS::Handle<JS::Value> aChunk,
     CloseAndRelease(aCx, NS_ERROR_DOM_WRONG_TYPE_ERR);
     return;
   }
-  chunk.ComputeState();
-
-  MOZ_DIAGNOSTIC_ASSERT(mBuffer.IsEmpty());
 
   // Let's take a copy of the data.
   // FIXME: We could sometimes avoid this copy by trying to write `chunk`
   // directly into `mPipeOut` eagerly, and only filling `mBuffer` if there isn't
   // enough space in the pipe's buffer.
-  if (!mBuffer.AppendElements(chunk.Data(), chunk.Length(), fallible)) {
+  nsTArray<uint8_t> buffer;
+  if (!chunk.AppendDataTo(buffer)) {
     CloseAndRelease(aCx, NS_ERROR_OUT_OF_MEMORY);
     return;
   }
 
+  uint32_t len = buffer.Length();
+  if (len == 0) {
+    // If there is nothing to read, let's do another reading.
+    OnOutputStreamReady(mPipeOut);
+    return;
+  }
+
+  MOZ_DIAGNOSTIC_ASSERT(mBuffer.IsEmpty());
+
+  mBuffer = std::move(buffer);
   mBufferOffset = 0;
-  mBufferRemaining = chunk.Length();
+  mBufferRemaining = mBuffer.Length();
 
   nsresult rv = WriteBuffer();
   if (NS_WARN_IF(NS_FAILED(rv))) {