Use updated request cancellation API.

Author: Tratcher

src/Microsoft.AspNet.StaticFiles/StaticFileContext.cs

@@ -319,14 +319,14 @@ public async Task SendAsync()
             var sendFile = _context.GetFeature<IHttpSendFileFeature>();
             if (sendFile != null && !string.IsNullOrEmpty(physicalPath))
             {
-                await sendFile.SendFileAsync(physicalPath, 0, _length, _request.CallCanceled);
+                await sendFile.SendFileAsync(physicalPath, 0, _length, _context.OnRequestAborted);
                 return;
             }
 
             Stream readStream = _fileInfo.CreateReadStream();
             try
             {
-                await StreamCopyOperation.CopyToAsync(readStream, _response.Body, _length, _request.CallCanceled);
+                await StreamCopyOperation.CopyToAsync(readStream, _response.Body, _length, _context.OnRequestAborted);
             }
             finally
             {
@@ -365,15 +365,15 @@ internal async Task SendRangeAsync()
             var sendFile = _context.GetFeature<IHttpSendFileFeature>();
             if (sendFile != null && !string.IsNullOrEmpty(physicalPath))
             {
-                await sendFile.SendFileAsync(physicalPath, start, length, _request.CallCanceled);
+                await sendFile.SendFileAsync(physicalPath, start, length, _context.OnRequestAborted);
                 return;
             }
 
             Stream readStream = _fileInfo.CreateReadStream();
             try
             {
                 readStream.Seek(start, SeekOrigin.Begin); // TODO: What if !CanSeek?
-                await StreamCopyOperation.CopyToAsync(readStream, _response.Body, length, _request.CallCanceled);
+                await StreamCopyOperation.CopyToAsync(readStream, _response.Body, length, _context.OnRequestAborted);
             }
             finally
             {