unread: Rename countInAllMessagesNarrow method

Fixes: #676

Author: Lalit3716

lib/model/unreads.dart

@@ -129,7 +129,7 @@ class Unreads extends ChangeNotifier {
   final int selfUserId;
 
   // TODO(#370): maintain this count incrementally, rather than recomputing from scratch
-  int countInAllMessagesNarrow() {
+  int countInCombinedFeedNarrow() {
     int c = 0;
     for (final messageIds in dms.values) {
       c = c + messageIds.length;
@@ -196,7 +196,7 @@ class Unreads extends ChangeNotifier {
   int countInNarrow(Narrow narrow) {
     switch (narrow) {
       case CombinedFeedNarrow():
-        return countInAllMessagesNarrow();
+        return countInCombinedFeedNarrow();
       case StreamNarrow():
         return countInStreamNarrow(narrow.streamId);
       case TopicNarrow():

test/model/unreads_test.dart

@@ -152,7 +152,7 @@ void main() {
   });
 
   group('count helpers', () {
-    test('countInAllMessagesNarrow', () async {
+    test('countInCombinedFeedNarrow', () async {
       final stream1 = eg.stream(streamId: 1, name: 'stream 1');
       final stream2 = eg.stream(streamId: 2, name: 'stream 2');
       final stream3 = eg.stream(streamId: 3, name: 'stream 3');
@@ -171,7 +171,7 @@ void main() {
         eg.dmMessage(from: eg.otherUser, to: [eg.selfUser], flags: []),
         eg.dmMessage(from: eg.thirdUser, to: [eg.selfUser], flags: []),
       ]);
-      check(model.countInAllMessagesNarrow()).equals(5);
+      check(model.countInCombinedFeedNarrow()).equals(5);
     });
 
     test('countInStream/Narrow', () async {