Bug 1304941 - reconnect onTabChanged listener before fetching the tablist;r=jryans

MozReview-Commit-ID: FZYDKH3F21O

--HG--
extra : rebase_source : 582f91c90362f6cffa932b1f7d49d46c061ac960

devtools/client/aboutdebugging/test/browser_tabs.js

@@ -42,6 +42,10 @@ add_task(function* () {
     yield waitForContentMutation(newTabTarget);
   }
 
+  // Then wait for title update, but on slow test runner, the title may already
+  // be set to the expected value
+  yield waitUntil(() => newTabTarget.title === TAB_URL);
+
   // Check that the new tab appears in the UI
   is(newTabTarget.textContent, "foo", "The tab title got updated");
   is(newTabTarget.title, TAB_URL, "The tab tooltip is the url");

devtools/server/actors/root.js

@@ -250,6 +250,12 @@ RootActor.prototype = {
                message: "This root actor has no browser tabs." };
     }
 
+    /*
+     * Now that a client has requested the list of tabs, we reattach the onListChanged
+     * listener in order to be notified if the list of tabs changes again in the future.
+     */
+    tabList.onListChanged = this._onTabListChanged;
+
     /*
      * Walk the tab list, accumulating the array of tab actors for the
      * reply, and moving all the actors to a new ActorPool. We'll
@@ -300,13 +306,6 @@ RootActor.prototype = {
       /* DebuggerServer.addGlobalActor support: name actors in 'listTabs' reply. */
       this._appendExtraActors(reply);
 
-      /*
-       * Now that we're actually going to report the contents of tabList to
-       * the client, we're responsible for letting the client know if it
-       * changes.
-       */
-      tabList.onListChanged = this._onTabListChanged;
-
       return reply;
     });
   },