Bug 1394121 Let legacy extensions be installed temporarily r=kmag

MozReview-Commit-ID: 4fiA8vvCjmr

--HG--
extra : rebase_source : 41b7a47f9da4c8f7ca863168c118d2f934446d07

toolkit/mozapps/extensions/internal/XPIProvider.jsm

@@ -784,7 +784,16 @@ function canRunInSafeMode(aAddon) {
 function isDisabledLegacy(addon) {
   return (!AddonSettings.ALLOW_LEGACY_EXTENSIONS &&
           LEGACY_TYPES.has(addon.type) &&
+
+          // Legacy add-ons are allowed in the system location.
           !addon._installLocation.isSystem &&
+
+          // Legacy extensions may be installed temporarily in
+          // non-release builds.
+          !(AppConstants.MOZ_ALLOW_LEGACY_EXTENSIONS &&
+            addon._installLocation.name == KEY_APP_TEMPORARY) &&
+
+          // Properly signed legacy extensions are allowed.
           addon.signedState !== AddonManager.SIGNEDSTATE_PRIVILEGED);
 }
 

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

@@ -819,3 +819,30 @@ add_task(async function() {
 
   await promiseRestartManager();
 });
+
+// Check that WebExtensions experiments can only be installed temporarily
+// in builds that allow legacy extensions.
+add_task(async function() {
+  const API_ID = "apiexperiment@tests.mozilla.org";
+  let xpi = createTempXPIFile({
+    id: API_ID,
+    name: "WebExtension Experiment",
+    version: "1.0",
+    type: 256,
+    targetApplications: [{
+      id: "xpcshell@tests.mozilla.org",
+      minVersion: "1",
+      maxVersion: "1"
+    }],
+  });
+
+  await AddonManager.installTemporaryAddon(xpi);
+  let addon = await promiseAddonByID(API_ID);
+
+  if (AppConstants.MOZ_ALLOW_LEGACY_EXTENSIONS) {
+    notEqual(addon, null, "Temporary install of WebExtension experiment succeeded");
+    addon.uninstall();
+  } else {
+    equal(addon, null, "Temporary install of WebExtension experiment was not allowed");
+  }
+});