Bug 1629951 - Ensure we terminate worker if prefs are changed causing worker to be impacted. r=gvn

Differential Revision: https://phabricator.services.mozilla.com/D70928

browser/components/newtab/lib/PersonalityProvider/PersonalityProvider.jsm

@@ -110,6 +110,9 @@ this.PersonalityProvider = class PersonalityProvider {
   teardown() {
     this.teardownSyncAttachment(RECIPE_NAME);
     this.teardownSyncAttachment(MODELS_NAME);
+    if (this._personalityProviderWorker) {
+      this._personalityProviderWorker.terminate();
+    }
   }
 
   setupSyncAttachment(collection) {

browser/components/newtab/test/unit/lib/PersonalityProvider/PersonalityProvider.test.js

@@ -130,6 +130,14 @@ describe("Personality Provider", () => {
       instance.teardown();
       assert.calledTwice(instance.teardownSyncAttachment);
     });
+    it("should terminate worker", () => {
+      const terminateStub = sandbox.stub().returns();
+      instance._personalityProviderWorker = {
+        terminate: terminateStub,
+      };
+      instance.teardown();
+      assert.calledOnce(terminateStub);
+    });
   });
   describe("#setupSyncAttachment", () => {
     it("should call remote settings on twice for setupSyncAttachment", () => {