ntp_snippets: fix ./fetch.py --short

When I broke out a function, I mixed up the request and the JSON for the
argument.

Review-Url: https://codereview.chromium.org/2849763003
Cr-Commit-Position: refs/heads/master@{#467982}

components/ntp_snippets/remote/fetch.py

@@ -195,9 +195,9 @@ def Authenticate(args, headers, client_id, client_secret):
   creds.apply(headers)
 
 
-def PrintShortResponse(r):
+def PrintShortResponse(j):
   now = datetime.datetime.now()
-  for category in r.json()["categories"]:
+  for category in j["categories"]:
     print("%s: " % category["localizedTitle"])
     for suggestion in category["suggestions"]:
       attribution = suggestion["attribution"]