Roll gsutil version to 4.15.

tools/telemetry/third_party/gsutilz/gslib/cloud_api_helper.py

Index: tools/telemetry/third_party/gsutilz/gslib/cloud_api_helper.py
diff --git a/tools/telemetry/third_party/gsutilz/gslib/cloud_api_helper.py b/tools/telemetry/third_party/gsutilz/gslib/cloud_api_helper.py
index c570bb15dfed8bfbfa58ef5836be3040d72e1940..f7fc930266ac03a687af9e78d34759000cc0f843 100644
--- a/tools/telemetry/third_party/gsutilz/gslib/cloud_api_helper.py
+++ b/tools/telemetry/third_party/gsutilz/gslib/cloud_api_helper.py
@@ -16,6 +16,8 @@
 
 from __future__ import absolute_import
 
+import json
+
 from gslib.cloud_api import ArgumentException
 
 
@@ -39,13 +41,12 @@ def ValidateDstObjectMetadata(dst_obj_metadata):
         'Object metadata supplied for destination object had no bucket name.')
 
 
-def GetDownloadSerializationDict(src_obj_metadata):
-  """Returns a baseline serialization dict from the source object metadata.
+def GetDownloadSerializationData(src_obj_metadata, progress=0):
+  """Returns download serialization data.
 
   There are four entries:
     auto_transfer: JSON-specific field, always False.
-    progress: How much of the download has already been completed. Caller
-              should override this value if the download is being resumed.
+    progress: How much of the download has already been completed.
     total_size: Total object size.
     url: Implementation-specific field used for saving a metadata get call.
          For JSON, this the download URL of the object.
@@ -53,13 +54,17 @@ def GetDownloadSerializationDict(src_obj_metadata):
 
   Args:
     src_obj_metadata: Object to be downloaded.
+    progress: See above.
 
   Returns:
-    Serialization dict for use with Cloud API GetObjectMedia.
+    Serialization data for use with Cloud API GetObjectMedia.
   """
-  return {
+
+  serialization_dict = {
       'auto_transfer': 'False',
-      'progress': 0,
+      'progress': progress,
       'total_size': src_obj_metadata.size,
       'url': src_obj_metadata.mediaLink
   }
+
+  return json.dumps(serialization_dict)