backend: Move json_success to callers vs helper functions.

As a preparatory step to refactoring json_success to accept
request as a parameter, change interface of helper functions:
`handle_deferred_message` in `views.message_send.py` and
`mute_topic` and `unmute_topic` in `views.muting.py`, so
that they return None or data for json_success.

Instead call json_sucess in the caller function, which already
has the HttpRequest as a parameter.

zerver/views/message_send.py

@@ -146,7 +146,7 @@ def handle_deferred_message(
     tz_guess: Optional[str],
     forwarder_user_profile: UserProfile,
     realm: Optional[Realm],
-) -> HttpResponse:
+) -> str:
     deliver_at = None
     local_tz = "UTC"
     if tz_guess:
@@ -179,7 +179,7 @@ def handle_deferred_message(
         realm=realm,
         forwarder_user_profile=forwarder_user_profile,
     )
-    return json_success({"deliver_at": str(deliver_at_usertz)})
+    return str(deliver_at_usertz)
 
 
 @has_request_variables
@@ -284,7 +284,7 @@ def send_message_backend(
         raise JsonableError(_("Missing deliver_at in a request for delayed message delivery"))
 
     if (delivery_type == "send_later" or delivery_type == "remind") and defer_until is not None:
-        return handle_deferred_message(
+        deliver_at = handle_deferred_message(
             sender,
             client,
             message_type_name,
@@ -297,6 +297,7 @@ def send_message_backend(
             forwarder_user_profile=user_profile,
             realm=realm,
         )
+        return json_success(data={"deliver_at": deliver_at})
 
     ret = check_send_message(
         sender,

zerver/views/muting.py

@@ -29,7 +29,7 @@ def mute_topic(
     stream_name: Optional[str],
     topic_name: str,
     date_muted: datetime.datetime,
-) -> HttpResponse:
+) -> None:
     if stream_name is not None:
         (stream, sub) = access_stream_by_name(user_profile, stream_name)
     else:
@@ -40,12 +40,14 @@ def mute_topic(
         raise JsonableError(_("Topic already muted"))
 
     do_mute_topic(user_profile, stream, topic_name, date_muted)
-    return json_success()
 
 
 def unmute_topic(
-    user_profile: UserProfile, stream_id: Optional[int], stream_name: Optional[str], topic_name: str
+    user_profile: UserProfile,
-) -> HttpResponse:
+    stream_id: Optional[int],
+    stream_name: Optional[str],
+    topic_name: str,
+) -> None:
     error = _("Topic is not muted")
 
     if stream_name is not None:
@@ -55,7 +57,6 @@ def unmute_topic(
         stream = access_stream_for_unmute_topic_by_id(user_profile, stream_id, error)
 
     do_unmute_topic(user_profile, stream, topic_name)
-    return json_success()
 
 
 @has_request_variables
@@ -71,20 +72,22 @@ def update_muted_topic(
     check_for_exactly_one_stream_arg(stream_id=stream_id, stream=stream)
 
     if op == "add":
-        return mute_topic(
+        mute_topic(
             user_profile=user_profile,
             stream_id=stream_id,
             stream_name=stream,
             topic_name=topic,
             date_muted=timezone_now(),
         )
+        return json_success()
     elif op == "remove":
-        return unmute_topic(
+        unmute_topic(
             user_profile=user_profile,
             stream_id=stream_id,
             stream_name=stream,
             topic_name=topic,
         )
+        return json_success()
 
 
 def mute_user(request: HttpRequest, user_profile: UserProfile, muted_user_id: int) -> HttpResponse: