feat (addon): #724 set home page to Activity Stream (#785)

* feat (addon): #724 set home page to Activity Stream

* keep track if user overrode the home page

* better I think

lib/ActivityStreams.js

@@ -11,6 +11,8 @@ const tabs = require("sdk/tabs");
 const simplePrefs = require("sdk/simple-prefs");
 const privateBrowsing = require("sdk/private-browsing");
 const windows = require("sdk/windows").browserWindows;
+const prefService = require("sdk/preferences/service");
+const ss = require("sdk/simple-storage");
 const {Memoizer} = require("lib/Memoizer");
 const {PlacesProvider} = require("lib/PlacesProvider");
 const {SearchProvider} = require("lib/SearchProvider");
@@ -57,14 +59,19 @@ const PLACES_CHANGES_EVENTS = [
   "bookmarkChanged"
 ];
 
+const HOME_PAGE_PREF = "browser.startup.homepage";
+
 function ActivityStreams(options = {}) {
   this.options = Object.assign({}, DEFAULT_OPTIONS, options);
   EventEmitter.decorate(this);
 
+  this._newTabURL = `${this.options.pageURL}#/`;
+
   this._setupPageMod();
   this._setupListeners();
   this._setupButton();
-  NewTabURL.override(`${this.options.pageURL}#/`);
+  NewTabURL.override(this._newTabURL);
+  this._setHomePage();
 
   Services.prefs.setIntPref("places.favicons.optimizeToDimension", 64);
 
@@ -517,6 +524,31 @@ ActivityStreams.prototype = {
     });
   },
 
+  /*
+   * Replace the home page with the ActivityStream new tab page.
+   */
+  _setHomePage() {
+    // Only hijack the home page if it isn't set by user or if it is set to
+    // about:home/about:blank
+    // AND the user didn't previously override the preference.
+    if (!ss.storage.homepageOverriden &&
+        (!prefService.isSet(HOME_PAGE_PREF) ||
+         ["about:home", "about:blank"].includes(prefService.get(HOME_PAGE_PREF)))) {
+      prefService.set(HOME_PAGE_PREF, this._newTabURL);
+    }
+  },
+
+  _unsetHomePage() {
+    if (prefService.get(HOME_PAGE_PREF) === this._newTabURL) {
+      // Reset home page back if user didn't change it.
+      prefService.reset(HOME_PAGE_PREF);
+    } else {
+      // The user changed the pref. Keep track of that so next time we don't
+      // hijack it again.
+      ss.storage.homepageOverriden = true;
+    }
+  },
+
   /**
    * The URLs for the app.
    */
@@ -550,6 +582,7 @@ ActivityStreams.prototype = {
       clearTimeout(this._placesCacheTimeoutID);
       this._previewProvider.uninit();
       NewTabURL.reset();
+      this._unsetHomePage();
       Services.prefs.clearUserPref("places.favicons.optimizeToDimension");
       this.workers.clear();
       this._removeListeners();

test/test-ActivityStreams-home-page.js

@@ -0,0 +1,38 @@
+"use strict";
+
+const test = require("sdk/test");
+const prefService = require("sdk/preferences/service");
+const ss = require("sdk/simple-storage");
+const {ActivityStreams} = require("lib/ActivityStreams");
+
+exports["test activity stream loads on home page when appropriate"] = function*(assert) {
+  prefService.reset("browser.startup.homepage");
+  let url = "http://foo.bar/baz";
+  let app = new ActivityStreams({pageURL: url});
+
+  // By default, the home page should be set to ActivityStream.
+  assert.equal(url + "#/", prefService.get("browser.startup.homepage"));
+
+  // Unload ActivityStream and it should be unset.
+  app.unload();
+  assert.ok(!prefService.isSet("browser.startup.homepage"));
+
+  // If the pref is already overriden, ActivityStream shouldn't change it.
+  prefService.set("browser.startup.homepage", "https://example.com");
+  app = new ActivityStreams({pageURL: url});
+  assert.equal("https://example.com", prefService.get("browser.startup.homepage"));
+  app.unload();
+  assert.equal("https://example.com", prefService.get("browser.startup.homepage"));
+
+  // If we override the pref and the user changes it back to about:home,
+  // ActivityStream shouldn't change it on next load.
+  prefService.reset("browser.startup.homepage");
+  ss.storage.homepageOverriden = true;
+  app = new ActivityStreams({pageURL: url});
+  assert.ok(!prefService.isSet("browser.startup.homepage"));
+  app.unload();
+  assert.ok(!prefService.isSet("browser.startup.homepage"));
+
+};
+
+test.run(exports);