Bug 1078365 - ""Feedback:LastUrl" should use JS-Java callbacks". r=margaret

mobile/android/base/BrowserApp.java

@@ -1398,7 +1398,7 @@ public class BrowserApp extends GeckoApp
             });
 
         } else if ("Feedback:LastUrl".equals(event)) {
-            getLastUrl();
+            getLastUrl(callback);
 
         } else if ("Feedback:MaybeLater".equals(event)) {
             resetFeedbackLaunchCount();
@@ -3017,7 +3017,7 @@ public class BrowserApp extends GeckoApp
         settings.edit().putInt(getPackageName() + ".feedback_launch_count", 0).apply();
     }
 
-    private void getLastUrl() {
+    private void getLastUrl(final EventCallback callback) {
         (new UIAsyncTask.WithoutParams<String>(ThreadUtils.getBackgroundHandler()) {
             @Override
             public synchronized String doInBackground() {
@@ -3038,9 +3038,7 @@ public class BrowserApp extends GeckoApp
 
             @Override
             public void onPostExecute(String url) {
-                // Don't bother sending a message if there is no URL.
-                if (url.length() > 0)
-                    GeckoAppShell.sendEventToGecko(GeckoEvent.createBroadcastEvent("Feedback:LastUrl", url));
+                callback.sendSuccess(url);
             }
         }).execute();
     }

mobile/android/chrome/content/aboutFeedback.js

@@ -58,8 +58,6 @@ function init() {
   document.getElementById("sumo-icon").src = helpSectionIcon;
   document.getElementById("sad-thanks-icon").src = sadThanksIcon;
 
-  window.addEventListener("unload", uninit, false);
-
   document.getElementById("open-play-store").addEventListener("click", openPlayStore, false);
   document.forms[0].addEventListener("submit", sendFeedback, false);
   for (let anchor of document.querySelectorAll(".no-thanks")) {
@@ -76,20 +74,14 @@ function init() {
   }, false);
 
   // Fill "Last visited site" input with most recent history entry URL.
-  Services.obs.addObserver(function observer(aSubject, aTopic, aData) {
+  Messaging.sendRequestForResult({ type: "Feedback:LastUrl" }).then(function(aData) {
     aData = aData.substring(0, 200);
     document.getElementById("last-url").value = aData;
     // Enable the parent div iff the URL is valid.
     if (aData.length != 0) {
       document.getElementById("last-url-div").style.display="block";
     }
-  }, "Feedback:LastUrl", false);
-
-  Messaging.sendRequest({ type: "Feedback:LastUrl" });
-}
-
-function uninit() {
-  Services.obs.removeObserver(this, "Feedback:LastUrl");
+  });
 }
 
 function switchSection(aSection) {