Logging: s/print/logging.info/

The function print sends the output to stdout disturbing the output of
the application.
Use logging instead which sends the logs to stderr by default or to the
destination configured by the aplication.

Author: Helen Koike

logging/google/cloud/logging/handlers/transports/background_thread.py

@@ -17,8 +17,6 @@
 Uses a background worker to log to Stackdriver Logging asynchronously.
 """
 
-from __future__ import print_function
-
 import atexit
 import logging
 import threading
@@ -195,7 +193,7 @@ def stop(self, grace_period=None):
             self._queue.put_nowait(_WORKER_TERMINATOR)
 
             if grace_period is not None:
-                print('Waiting up to %d seconds.' % (grace_period,))
+                logging.info('Waiting up to %d seconds.' % (grace_period,))
 
             self._thread.join(timeout=grace_period)
 
@@ -214,14 +212,15 @@ def _main_thread_terminated(self):
             return
 
         if not self._queue.empty():
-            print(
+            logging.info(
                 'Program shutting down, attempting to send %d queued log '
                 'entries to Stackdriver Logging...' % (self._queue.qsize(),))
 
         if self.stop(self._grace_period):
-            print('Sent all pending logs.')
+            logging.info('Sent all pending logs.')
         else:
-            print('Failed to send %d pending logs.' % (self._queue.qsize(),))
+            logging.info(
+                'Failed to send %d pending logs.' % (self._queue.qsize(),))
 
     def enqueue(self, record, message, resource=None, labels=None):
         """Queues a log entry to be written by the background thread.