message: Fire map callback if map async operation fails
diff: @@ -271,7 +271,7 @@ namespace dawn_native {
  mState = BufferState::Mapped;
  if (GetDevice()->ConsumedError(MapReadAsyncImpl(mMapSerial))) {
  - // TODO(natlee@microsoft.com): if map op fails fire callback with DEVICE_LOST status
  + CallMapReadCallback(mMapSerial, WGPUBufferMapAsyncStatus_DeviceLost, nullptr, 0);
  return;
  }
  @@ -312,7 +312,7 @@ namespace dawn_native {
  mState = BufferState::Mapped;
  if (GetDevice()->ConsumedError(MapWriteAsyncImpl(mMapSerial))) {
  - // TODO(natlee@microsoft.com): if map op fails fire callback with DEVICE_LOST status
  + CallMapWriteCallback(mMapSerial, WGPUBufferMapAsyncStatus_DeviceLost, nullptr, 0);
  return;
  }
  