Bug 1094821 - Make it possible for an application to load extra themes into LightweightThemeManager.usedThemes;r=Gijs

When calling addBuiltInTheme, theme objects are stored in a Map keyed on ID
and are appended onto the usedThemes array.  These aren't removeable and don't
get stored in the pref.

toolkit/mozapps/extensions/LightweightThemeManager.jsm

@@ -95,13 +95,19 @@ var _themeIDBeingDisabled = null;
 this.LightweightThemeManager = {
   get name() "LightweightThemeManager",
 
+  // Themes that can be added for an application.  They can't be removed, and
+  // will always show up at the top of the list.
+  _builtInThemes: new Map(),
+
   get usedThemes () {
+    let themes = [];
     try {
-      return JSON.parse(_prefs.getComplexValue("usedThemes",
-                                               Ci.nsISupportsString).data);
-    } catch (e) {
-      return [];
-    }
+      themes = JSON.parse(_prefs.getComplexValue("usedThemes",
+                                                 Ci.nsISupportsString).data);
+    } catch (e) { }
+
+    themes.push(...this._builtInThemes.values());
+    return themes;
   },
 
   get currentTheme () {
@@ -152,7 +158,7 @@ this.LightweightThemeManager = {
 
   forgetUsedTheme: function LightweightThemeManager_forgetUsedTheme(aId) {
     let theme = this.getUsedTheme(aId);
-    if (!theme)
+    if (!theme || LightweightThemeManager._builtInThemes.has(theme.id))
       return;
 
     let wrapper = new AddonWrapper(theme);
@@ -168,6 +174,30 @@ this.LightweightThemeManager = {
     AddonManagerPrivate.callAddonListeners("onUninstalled", wrapper);
   },
 
+  addBuiltInTheme: function LightweightThemeManager_addBuiltInTheme(theme) {
+    if (!theme || !theme.id || this.usedThemes.some(t => t.id == theme.id)) {
+      throw new Error("Trying to add invalid builtIn theme");
+    }
+
+    this._builtInThemes.set(theme.id, theme);
+  },
+
+  forgetBuiltInTheme: function LightweightThemeManager_forgetBuiltInTheme(id) {
+    if (!this._builtInThemes.has(id)) {
+      let currentTheme = this.currentTheme;
+      if (currentTheme && currentTheme.id == id) {
+        this.currentTheme = null;
+      }
+    }
+    return this._builtInThemes.delete(id);
+  },
+
+  clearBuiltInThemes: function LightweightThemeManager_clearBuiltInThemes() {
+    for (let id of this._builtInThemes.keys()) {
+      this.forgetBuiltInTheme(id);
+    }
+  },
+
   previewTheme: function LightweightThemeManager_previewTheme(aData) {
     let cancel = Cc["@mozilla.org/supports-PRBool;1"].createInstance(Ci.nsISupportsPRBool);
     cancel.data = false;
@@ -493,7 +523,11 @@ function AddonWrapper(aTheme) {
   });
 
   this.__defineGetter__("permissions", function AddonWrapper_permissionsGetter() {
-    let permissions = AddonManager.PERM_CAN_UNINSTALL;
+    let permissions = 0;
+
+    // Do not allow uninstall of builtIn themes.
+    if (!LightweightThemeManager._builtInThemes.has(aTheme.id))
+      permissions = AddonManager.PERM_CAN_UNINSTALL;
     if (this.userDisabled)
       permissions |= AddonManager.PERM_CAN_ENABLE;
     else
@@ -710,6 +744,9 @@ function _makeURI(aURL, aBaseURI)
   Services.io.newURI(aURL, null, aBaseURI);
 
 function _updateUsedThemes(aList) {
+  // Remove app-specific themes before saving them to the usedThemes pref.
+  aList = aList.filter(theme => !LightweightThemeManager._builtInThemes.has(theme.id));
+
   // Send uninstall events for all themes that need to be removed.
   while (aList.length > _maxUsedThemes) {
     let wrapper = new AddonWrapper(aList[aList.length - 1]);

toolkit/mozapps/extensions/test/xpcshell/test_LightweightThemeManager.js

@@ -19,18 +19,20 @@ function dummy(id) {
   };
 }
 
+function hasPermission(aAddon, aPerm) {
+  var perm = AddonManager["PERM_CAN_" + aPerm.toUpperCase()];
+  return !!(aAddon.permissions & perm);
+}
+
 function run_test() {
   createAppInfo("xpcshell@tests.mozilla.org", "XPCShell", "1", "1.9");
   startupManager();
 
   Services.prefs.setIntPref("lightweightThemes.maxUsedThemes", 8);
 
-  var temp = {};
-  Components.utils.import("resource://gre/modules/LightweightThemeManager.jsm", temp);
-  do_check_eq(typeof temp.LightweightThemeManager, "object");
-
-  var ltm = temp.LightweightThemeManager;
+  let {LightweightThemeManager: ltm} = Components.utils.import("resource://gre/modules/LightweightThemeManager.jsm", {});
 
+  do_check_eq(typeof ltm, "object");
   do_check_eq(typeof ltm.usedThemes, "object");
   do_check_eq(ltm.usedThemes.length, 0);
   do_check_eq(ltm.currentTheme, null);
@@ -511,4 +513,86 @@ function run_test() {
   Services.prefs.clearUserPref("lightweightThemes.maxUsedThemes");
 
   do_check_eq(ltm.usedThemes.length, 30);
+
+  let usedThemes = ltm.usedThemes;
+  for (let theme of usedThemes) {
+    ltm.forgetUsedTheme(theme.id);
+  }
+
+  // Check builtInTheme functionality for Bug 1094821
+  do_check_eq(ltm._builtInThemes.toString(), "[object Map]");
+  do_check_eq([...ltm._builtInThemes.entries()].length, 0);
+  do_check_eq(ltm.usedThemes.length, 0);
+
+  ltm.addBuiltInTheme(dummy("builtInTheme0"));
+  do_check_eq([...ltm._builtInThemes].length, 1);
+  do_check_eq(ltm.usedThemes.length, 1);
+  do_check_eq(ltm.usedThemes[0].id, "builtInTheme0");
+
+  ltm.addBuiltInTheme(dummy("builtInTheme1"));
+  do_check_eq([...ltm._builtInThemes].length, 2);
+  do_check_eq(ltm.usedThemes.length, 2);
+  do_check_eq(ltm.usedThemes[1].id, "builtInTheme1");
+
+  // Clear all and then re-add
+  ltm.clearBuiltInThemes();
+  do_check_eq([...ltm._builtInThemes].length, 0);
+  do_check_eq(ltm.usedThemes.length, 0);
+
+  ltm.addBuiltInTheme(dummy("builtInTheme0"));
+  ltm.addBuiltInTheme(dummy("builtInTheme1"));
+  do_check_eq([...ltm._builtInThemes].length, 2);
+  do_check_eq(ltm.usedThemes.length, 2);
+
+  do_test_pending();
+
+  AddonManager.getAddonByID("builtInTheme0@personas.mozilla.org", aAddon => {
+    // App specific theme can't be uninstalled or disabled,
+    // but can be enabled (since it isn't already applied).
+    do_check_eq(hasPermission(aAddon, "uninstall"), false);
+    do_check_eq(hasPermission(aAddon, "disable"), false);
+    do_check_eq(hasPermission(aAddon, "enable"), true);
+
+    ltm.currentTheme = dummy("x0");
+    do_check_eq([...ltm._builtInThemes].length, 2);
+    do_check_eq(ltm.usedThemes.length, 3);
+    do_check_eq(ltm.usedThemes[0].id, "x0");
+    do_check_eq(ltm.currentTheme.id, "x0");
+    do_check_eq(ltm.usedThemes[1].id, "builtInTheme0");
+    do_check_eq(ltm.usedThemes[2].id, "builtInTheme1");
+
+    Assert.throws(() => { ltm.addBuiltInTheme(dummy("builtInTheme0")) },
+      "Exception is thrown adding a duplicate theme");
+    Assert.throws(() => { ltm.addBuiltInTheme("not a theme object") },
+      "Exception is thrown adding an invalid theme");
+
+    AddonManager.getAddonByID("x0@personas.mozilla.org", aAddon => {
+      // Currently applied (non-app-specific) can be uninstalled or disabled,
+      // but can't be enabled (since it's already applied).
+      do_check_eq(hasPermission(aAddon, "uninstall"), true);
+      do_check_eq(hasPermission(aAddon, "disable"), true);
+      do_check_eq(hasPermission(aAddon, "enable"), false);
+
+      ltm.forgetUsedTheme("x0");
+      do_check_eq(ltm.currentTheme, null);
+
+      // Removing the currently applied app specific theme should unapply it
+      ltm.currentTheme = ltm.getUsedTheme("builtInTheme0");
+      do_check_eq(ltm.currentTheme.id, "builtInTheme0");
+      do_check_true(ltm.forgetBuiltInTheme("builtInTheme0"));
+      do_check_eq(ltm.currentTheme, null);
+
+      do_check_eq([...ltm._builtInThemes].length, 1);
+      do_check_eq(ltm.usedThemes.length, 1);
+
+      do_check_true(ltm.forgetBuiltInTheme("builtInTheme1"));
+      do_check_false(ltm.forgetBuiltInTheme("not-an-existing-theme-id"));
+
+      do_check_eq([...ltm._builtInThemes].length, 0);
+      do_check_eq(ltm.usedThemes.length, 0);
+      do_check_eq(ltm.currentTheme, null);
+
+      do_test_finished();
+    });
+  });
 }