util: Kill off set_topic_links/get_topic_links.

These functions were just shims that were
used in the somewhat painful migration from
subject_* to topic_*.

The commit 4572be8c27
fixed it so that the client never needs to
deal with "subject_links".

So now we just go back to simpler code:

    message.topic_links = links
    links = message.topic_links

frontend_tests/node_tests/markdown.js

@@ -3,7 +3,6 @@ set_global('katex', zrequire('katex', 'katex/dist/katex.min.js'));
 set_global('marked', zrequire('marked', 'third/marked/lib/marked'));
 set_global('i18n', global.stub_i18n);
 
-const util = zrequire('util');
 zrequire('fenced_code');
 zrequire('stream_data');
 zrequire('people');
@@ -441,50 +440,50 @@ run_test('marked', () => {
 run_test('topic_links', () => {
     let message = {type: 'stream', topic: "No links here"};
     markdown.add_topic_links(message);
-    assert.equal(util.get_topic_links(message).length, 0);
+    assert.equal(message.topic_links.length, 0);
 
     message = {type: 'stream', topic: "One #123 link here"};
     markdown.add_topic_links(message);
-    assert.equal(util.get_topic_links(message).length, 1);
-    assert.equal(util.get_topic_links(message)[0], "https://trac.zulip.net/ticket/123");
+    assert.equal(message.topic_links.length, 1);
+    assert.equal(message.topic_links[0], "https://trac.zulip.net/ticket/123");
 
     message = {type: 'stream', topic: "Two #123 #456 link here"};
     markdown.add_topic_links(message);
-    assert.equal(util.get_topic_links(message).length, 2);
-    assert.equal(util.get_topic_links(message)[0], "https://trac.zulip.net/ticket/123");
-    assert.equal(util.get_topic_links(message)[1], "https://trac.zulip.net/ticket/456");
+    assert.equal(message.topic_links.length, 2);
+    assert.equal(message.topic_links[0], "https://trac.zulip.net/ticket/123");
+    assert.equal(message.topic_links[1], "https://trac.zulip.net/ticket/456");
 
     message = {type: 'stream', topic: "New ZBUG_123 link here"};
     markdown.add_topic_links(message);
-    assert.equal(util.get_topic_links(message).length, 1);
-    assert.equal(util.get_topic_links(message)[0], "https://trac2.zulip.net/ticket/123");
+    assert.equal(message.topic_links.length, 1);
+    assert.equal(message.topic_links[0], "https://trac2.zulip.net/ticket/123");
 
     message = {type: 'stream', topic: "New ZBUG_123 with #456 link here"};
     markdown.add_topic_links(message);
-    assert.equal(util.get_topic_links(message).length, 2);
-    assert(util.get_topic_links(message).includes("https://trac2.zulip.net/ticket/123"));
-    assert(util.get_topic_links(message).includes("https://trac.zulip.net/ticket/456"));
+    assert.equal(message.topic_links.length, 2);
+    assert(message.topic_links.includes("https://trac2.zulip.net/ticket/123"));
+    assert(message.topic_links.includes("https://trac.zulip.net/ticket/456"));
 
     message = {type: 'stream', topic: "One ZGROUP_123:45 link here"};
     markdown.add_topic_links(message);
-    assert.equal(util.get_topic_links(message).length, 1);
-    assert.equal(util.get_topic_links(message)[0], "https://zone_45.zulip.net/ticket/123");
+    assert.equal(message.topic_links.length, 1);
+    assert.equal(message.topic_links[0], "https://zone_45.zulip.net/ticket/123");
 
     message = {type: 'stream', topic: "Hello https://google.com"};
     markdown.add_topic_links(message);
-    assert.equal(util.get_topic_links(message).length, 1);
-    assert.equal(util.get_topic_links(message)[0], "https://google.com");
+    assert.equal(message.topic_links.length, 1);
+    assert.equal(message.topic_links[0], "https://google.com");
 
     message = {type: 'stream', topic: "#456 https://google.com https://github.com"};
     markdown.add_topic_links(message);
-    assert.equal(util.get_topic_links(message).length, 3);
-    assert(util.get_topic_links(message).includes("https://google.com"));
-    assert(util.get_topic_links(message).includes("https://github.com"));
-    assert(util.get_topic_links(message).includes("https://trac.zulip.net/ticket/456"));
+    assert.equal(message.topic_links.length, 3);
+    assert(message.topic_links.includes("https://google.com"));
+    assert(message.topic_links.includes("https://github.com"));
+    assert(message.topic_links.includes("https://trac.zulip.net/ticket/456"));
 
     message = {type: "not-stream"};
     markdown.add_topic_links(message);
-    assert.equal(util.get_topic_links(message).length, 0);
+    assert.equal(message.topic_links.length, 0);
 });
 
 run_test('message_flags', () => {

static/js/echo.js

@@ -292,7 +292,7 @@ exports.process_from_server = function process_from_server(messages) {
         // the backend.
         client_message.timestamp = message.timestamp;
 
-        util.set_topic_links(client_message, util.get_topic_links(message));
+        client_message.topic_links = message.topic_links;
         client_message.is_me_message = message.is_me_message;
         client_message.submessages = message.submessages;
 

static/js/markdown.js

@@ -175,7 +175,7 @@ exports.apply_markdown = function (message) {
 
 exports.add_topic_links = function (message) {
     if (message.type !== 'stream') {
-        util.set_topic_links(message, []);
+        message.topic_links = [];
         return;
     }
     const topic = util.get_message_topic(message);
@@ -207,7 +207,7 @@ exports.add_topic_links = function (message) {
         links = links.concat(match);
     }
 
-    util.set_topic_links(message, links);
+    message.topic_links = links;
 };
 
 exports.is_status_message = function (raw_content) {

static/js/message_events.js

@@ -197,7 +197,7 @@ exports.update_messages = function update_messages(events) {
                 unread.update_unread_topics(msg, event);
 
                 util.set_message_topic(msg, new_topic);
-                util.set_topic_links(msg, util.get_topic_links(event));
+                msg.topic_links = event.topic_links;
 
                 // Add the recent topics entry for the new topics; must
                 // be called after we call set_message_topic.

static/js/message_list_view.js

@@ -182,7 +182,7 @@ function populate_group_from_message_container(group, message_container) {
         group.display_reply_to = message_store.get_pm_full_names(message_container.msg);
     }
     group.display_recipient = message_container.msg.display_recipient;
-    group.topic_links = util.get_topic_links(message_container.msg);
+    group.topic_links = message_container.msg.topic_links;
 
     set_topic_edit_properties(group, message_container.msg);
     render_group_display_date(group, message_container);

static/js/util.js

@@ -234,14 +234,6 @@ exports.sorted_ids = function (ids) {
     return id_list;
 };
 
-exports.set_topic_links = function (obj, topic_links) {
-    obj.topic_links = topic_links;
-};
-
-exports.get_topic_links = function (obj) {
-    return obj.topic_links;
-};
-
 exports.set_match_data = function (target, source) {
     target.match_subject = source.match_subject;
     target.match_content = source.match_content;