fix: Add Content-Length header in media response (#738)

Author: animesh-g

gcs/object.py

@@ -531,6 +531,7 @@ def streamer():
             headers["Content-Type"] = "application/octet-stream"
 
         headers["x-goog-stored-content-length"] = self.metadata.size
+        headers["Content-Length"] = self.metadata.size
 
         if self.metadata.content_encoding:
             headers["x-goog-stored-content-encoding"] = self.metadata.content_encoding

tests/test_object.py

@@ -667,6 +667,8 @@ def test_rest_media(self):
         self.assertIn("x-goog-generation", response.headers)
         self.assertIn("x-goog-metageneration", response.headers)
         self.assertIn("x-goog-storage-class", response.headers)
+        self.assertIn("Content-Length", response.headers)
+        self.assertEqual(response.headers["Content-Length"], str(len(blob.media)))
 
         cases = {
             "bytes=4-9": (b"vexing", "4-9"),