Make compressedBackendFormat accessible from GrContextThreadSafeProxy

Not having this available on GrContextThreadSafeProxy was an oversight.
This will allow Chrome to correctly prepare the correct type of compressed promise image.

Change-Id: I3002609fef00a130fe409f318ae0f442ef7591d6
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/437016
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
diff --git a/include/gpu/GrDirectContext.h b/include/gpu/GrDirectContext.h
index 532d41e..66703bd 100644
--- a/include/gpu/GrDirectContext.h
+++ b/include/gpu/GrDirectContext.h
@@ -655,6 +655,7 @@
      * Retrieve the GrBackendFormat for a given SkImage::CompressionType. This is
      * guaranteed to match the backend format used by the following
      * createCompressedBackendTexture methods that take a CompressionType.
+     *
      * The caller should check that the returned format is valid.
      */
     using GrRecordingContext::compressedBackendFormat;