Update samples to support latest Google Cloud Python [(googleapis#656)](

GoogleCloudPlatform/python-docs-samples#656)

samples/snippets/export.py

@@ -23,13 +23,7 @@ def list_sinks():
     """Lists all sinks."""
     logging_client = logging.Client()
 
-    sinks = []
-    token = None
-    while True:
-        new_sinks, token = logging_client.list_sinks(page_token=token)
-        sinks.extend(new_sinks)
-        if token is None:
-            break
+    sinks = list(logging_client.list_sinks())
 
     if not sinks:
         print('No sinks.')

samples/snippets/requirements.txt

@@ -1 +1 @@
-google-cloud-logging==0.20.0
+google-cloud-logging==0.21.0

samples/snippets/snippets.py

@@ -56,16 +56,7 @@ def list_entries(logger_name):
 
     print('Listing entries for logger {}:'.format(logger.name))
 
-    entries = []
-    page_token = None
-
-    while True:
-        new_entries, page_token = logger.list_entries(page_token=page_token)
-        entries.extend(new_entries)
-        if not page_token:
-            break
-
-    for entry in entries:
+    for entry in logger.list_entries():
         timestamp = entry.timestamp.isoformat()
         print('* {}: {}'.format
               (timestamp, entry.payload))