Roll gsutil version to 4.15.

tools/telemetry/third_party/gsutilz/third_party/apitools/samples/storage_sample/uploads_test.py

Index: tools/telemetry/third_party/gsutilz/third_party/apitools/samples/storage_sample/uploads_test.py
diff --git a/tools/telemetry/third_party/gsutilz/third_party/apitools/samples/storage_sample/uploads_test.py b/tools/telemetry/third_party/gsutilz/third_party/apitools/samples/storage_sample/uploads_test.py
index ad4416f60748a789723ae36b37006400f7035e8d..4eb5abad37d4b67a2570ce425e98f9ec37c65d1e 100644
--- a/tools/telemetry/third_party/gsutilz/third_party/apitools/samples/storage_sample/uploads_test.py
+++ b/tools/telemetry/third_party/gsutilz/third_party/apitools/samples/storage_sample/uploads_test.py
@@ -103,6 +103,20 @@ class UploadsTest(unittest.TestCase):
         response = self.__InsertFile(filename, request=request)
         self.assertEqual(size, response.size)
 
+    def testStreamMedia(self):
+        filename = 'ten_meg_file'
+        size = 10 << 20
+        self.__ResetUpload(size, auto_transfer=False)
+        self.__upload.strategy = 'resumable'
+        self.__upload.total_size = size
+        request = self.__InsertRequest(filename)
+        initial_response = self.__client.objects.Insert(
+            request, upload=self.__upload)
+        self.assertIsNotNone(initial_response)
+        self.assertEqual(0, self.__buffer.tell())
+        self.__upload.StreamMedia()
+        self.assertEqual(size, self.__buffer.tell())
+
     def testBreakAndResumeUpload(self):
         filename = ('ten_meg_file_' +
                     ''.join(random.sample(string.ascii_letters, 5)))