patch

gistfile1.patch

diff --git a/browser/components/preferences/in-content/home.js b/browser/components/preferences/in-content/home.js
index e6e02c24c9e1..20cbf7db56e7 100644
--- a/browser/components/preferences/in-content/home.js
+++ b/browser/components/preferences/in-content/home.js
@@ -31,13 +31,45 @@ Preferences.addAll([
 const HOMEPAGE_OVERRIDE_KEY = "homepage_override";
 const URL_OVERRIDES_TYPE = "url_overrides";
 const NEW_TAB_KEY = "newTabURL";
+const ACTIVITY_STREAM_PREF_BRANCH = "browser.newtabpage.activity-stream.";
+const NEWTAB_ENABLED_PREF = "browser.newtabpage.enabled";
+
+const homePagePreferenceObserver = {
+  _initialized: false,
+
+  init() {
+    if (this._initialized) {
+      return;
+    }
+
+    Services.prefs.addObserver(ACTIVITY_STREAM_PREF_BRANCH, this);
+    Services.prefs.addObserver("browser.startup.homepage", this);
+    Services.prefs.addObserver(NEWTAB_ENABLED_PREF, this);
+
+    window.addEventListener("unload", () => {
+      Services.prefs.removeObserver(ACTIVITY_STREAM_PREF_BRANCH, this);
+      Services.prefs.removeObserver("browser.startup.homepage", this);
+      Services.prefs.removeObserver(NEWTAB_ENABLED_PREF, this);
+
+      this._initialized = false;
+    });
+
+    this._initialized = true;
+  },
+
+  observe(aSubject, aTopic, aData) {
+    if (aTopic != "nsPref:changed") {
+      return;
+    }
+
+    gHomePane.updateDefaultBtn();
+  },
+}
 
 let gHomePane = {
   HOME_MODE_FIREFOX_HOME: "0",
   HOME_MODE_BLANK: "1",
   HOME_MODE_CUSTOM: "2",
-  NEWTAB_ENABLED_PREF: "browser.newtabpage.enabled",
-
   /**
    * _handleNewTabOverrides: disables new tab settings UI. Called by
    * an observer in ._watchNewTab that watches for new tab url changes
@@ -221,7 +253,7 @@ let gHomePane = {
   },
 
   syncFromNewTabPref() {
-    const newtabPref = Preferences.get(this.NEWTAB_ENABLED_PREF);
+    const newtabPref = Preferences.get(NEWTAB_ENABLED_PREF);
     return newtabPref.value ? this.HOME_MODE_FIREFOX_HOME : this.HOME_MODE_BLANK;
   },
 
@@ -327,7 +359,7 @@ let gHomePane = {
 
   restoreDefaultHomePage() {
     const homePref = Preferences.get("browser.startup.homepage");
-    const newtabPref = Preferences.get(this.NEWTAB_ENABLED_PREF);
+    const newtabPref = Preferences.get(NEWTAB_ENABLED_PREF);
     homePref.value = homePref.defaultValue;
     newtabPref.value = newtabPref.defaultValue;
   },
@@ -354,6 +386,31 @@ let gHomePane = {
     homePref.value = value;
   },
 
+  _changedHomeTabDefaultPrefs() {
+    const homeContentChanged = Preferences.getAll().filter(pref => pref.id.includes("activity-stream"))
+      .some(pref => pref.hasUserValue);
+    const homePref = Preferences.get("browser.startup.homepage");
+    const newtabPref = Preferences.get(NEWTAB_ENABLED_PREF);
+
+    return homeContentChanged ||
+      (homePref.value !== homePref.defaultValue) ||
+      newtabPref.hasUserValue;
+  },
+
+  updateDefaultBtn() {
+    const btn = document.getElementById("restoreDefaultHomePageBtn");
+    const prefChanged = this._changedHomeTabDefaultPrefs();
+    btn.style.visibility = prefChanged ? "visible" : "hidden";
+  },
+
+  restoreDefaultsForHomeTab() {
+    this.restoreDefaultHomePage();
+    Preferences.getAll().filter(pref => pref.id.includes("activity-stream"))
+      .forEach(pref => pref.value = pref.defaultValue);
+
+    document.getElementById("restoreDefaultHomePageBtn").style.visibility = "hidden";
+  },
+
   init() {
     // Event Listeners
     document.getElementById("homeMode").addEventListener("command", this.onMenuChange.bind(this));
@@ -361,7 +418,7 @@ let gHomePane = {
     document.getElementById("homePageUrl").addEventListener("input", this.onCustomHomePageInput.bind(this));
     document.getElementById("useCurrentBtn").addEventListener("command", this.setHomePageToCurrent.bind(this));
     document.getElementById("useBookmarkBtn").addEventListener("command", this.setHomePageToBookmark.bind(this));
-    document.getElementById("restoreDefaultHomePageBtn").addEventListener("command", this.restoreDefaultHomePage.bind(this));
+    document.getElementById("restoreDefaultHomePageBtn").addEventListener("command", this.restoreDefaultsForHomeTab.bind(this));
 
     this._updateUseCurrentButton();
     window.addEventListener("focus", this._updateUseCurrentButton.bind(this));
@@ -373,6 +430,7 @@ let gHomePane = {
     document.getElementById("disableNewTabExtension").addEventListener("command",
       makeDisableControllingExtension(URL_OVERRIDES_TYPE, NEW_TAB_KEY));
 
+    homePagePreferenceObserver.init();
     // Notify observers that the UI is now ready
     Services.obs.notifyObservers(window, "home-pane-loaded");
   }
diff --git a/browser/extensions/activity-stream/lib/AboutPreferences.jsm b/browser/extensions/activity-stream/lib/AboutPreferences.jsm
index a4a3748084fa..826190a6f698 100644
--- a/browser/extensions/activity-stream/lib/AboutPreferences.jsm
+++ b/browser/extensions/activity-stream/lib/AboutPreferences.jsm
@@ -65,6 +65,9 @@ const CUSTOM_CSS = `
 }
 `;
 
+const NEWTAB_ENABLED_PREF = "browser.newtabpage.enabled";
+const STARTUP_HOMEPAGE_PREF = "browser.startup.homepage";
+
 this.AboutPreferences = class AboutPreferences {
   init() {
     Services.obs.addObserver(this, PREFERENCES_LOADED_EVENT);
@@ -126,6 +129,7 @@ this.AboutPreferences = class AboutPreferences {
     // Helper to create a new element and append it
     const createAppend = (tag, parent) => parent.appendChild(
       document.createElementNS(XUL_NS, tag));
+    const restoreDefaultPrefsBtn = document.getElementById("restoreDefaultHomePageBtn");
 
     // Helper to get strings and format with values if necessary
     const formatString = id => {
@@ -149,8 +153,19 @@ this.AboutPreferences = class AboutPreferences {
 
       // Prevent changing the UI if the preference can't be changed
       element.disabled = Preferences.get(fullPref).locked;
+
+      // TODO
+      if (Preferences.get(fullPref).hasUserValue) {
+        restoreDefaultPrefsBtn.style.visibility = "visible";
+      }
     };
 
+    const homePref = Preferences.get(STARTUP_HOMEPAGE_PREF);
+    const newtabPref = Preferences.get(NEWTAB_ENABLED_PREF);
+    if ((homePref.value === homePref.defaultValue) && !newtabPref.hasUserValue) {
+      restoreDefaultPrefsBtn.style.visibility = "hidden";
+    }
+
     // Add in custom styling
     document.insertBefore(document.createProcessingInstruction("xml-stylesheet",
       `href="data:text/css,${encodeURIComponent(CUSTOM_CSS)}" type="text/css"`),