unreads [nfc]: Rename countInChannel from "stream", to match its twin

This way its name continues to parallel that of countInChannelNarrow.

Also say "channel" in the two methods' docs.

Author: gnprice

lib/model/unreads.dart

@@ -144,16 +144,16 @@ class Unreads extends ChangeNotifier {
     return c;
   }
 
-  /// The "strict" unread count for this stream,
+  /// The "strict" unread count for this channel,
   /// using [ChannelStore.isTopicVisible].
   ///
-  /// If the stream is muted, this will count only topics that are
+  /// If the channel is muted, this will count only topics that are
   /// actively unmuted.
   ///
   /// For a count that's appropriate in UI contexts that are focused
-  /// specifically on this stream, see [countInChannelNarrow].
+  /// specifically on this channel, see [countInChannelNarrow].
   // TODO(#370): maintain this count incrementally, rather than recomputing from scratch
-  int countInStream(int streamId) {
+  int countInChannel(int streamId) {
     final topics = streams[streamId];
     if (topics == null) return 0;
     int c = 0;
@@ -165,14 +165,14 @@ class Unreads extends ChangeNotifier {
     return c;
   }
 
-  /// The "broad" unread count for this stream,
+  /// The "broad" unread count for this channel,
   /// using [ChannelStore.isTopicVisibleInStream].
   ///
   /// This includes topics that have no visibility policy of their own,
-  /// even if the stream itself is muted.
+  /// even if the channel itself is muted.
   ///
   /// For a count that's appropriate in UI contexts that are not already
-  /// focused on this stream, see [countInStream].
+  /// focused on this channel, see [countInChannel].
   // TODO(#370): maintain this count incrementally, rather than recomputing from scratch
   int countInChannelNarrow(int streamId) {
     final topics = streams[streamId];

lib/widgets/subscription_list.dart

@@ -187,7 +187,7 @@ class _SubscriptionList extends StatelessWidget {
       itemCount: subscriptions.length,
       itemBuilder: (BuildContext context, int index) {
         final subscription = subscriptions[index];
-        final unreadCount = unreadsModel!.countInStream(subscription.streamId);
+        final unreadCount = unreadsModel!.countInChannel(subscription.streamId);
         // TODO(#712): if stream muted, show a dot for unreads
         return SubscriptionItem(subscription: subscription, unreadCount: unreadCount);
     });

test/model/unreads_test.dart

@@ -189,13 +189,13 @@ void main() {
         eg.streamMessage(stream: stream, topic: 'b', flags: []),
         eg.streamMessage(stream: stream, topic: 'c', flags: []),
       ]);
-      check(model.countInStream       (stream.streamId)).equals(5);
+      check(model.countInChannel      (stream.streamId)).equals(5);
       check(model.countInChannelNarrow(stream.streamId)).equals(5);
 
       await channelStore.handleEvent(SubscriptionUpdateEvent(id: 1,
         streamId: stream.streamId,
         property: SubscriptionProperty.isMuted, value: true));
-      check(model.countInStream       (stream.streamId)).equals(2);
+      check(model.countInChannel      (stream.streamId)).equals(2);
       check(model.countInChannelNarrow(stream.streamId)).equals(5);
     });