Bug 1728326 - Add GetRegistrationForAddonPrincipal to nsIServiceWorkerManager. r=asuth

This patch introduces a new getRegistrationForAddonPrincipal to nsIServiceWorkerManager.
This method is similar to the existing getRegistrationForPrincipal but:
- similarly to registerForAddonPrincipal it only gets the extension principal as its only
  input parameter.
- unlike getRegistrationForPrincipal, it doesn't throw if the registration has not been found
  (e.g. because it was already unregistered when the method was called).

Differential Revision: https://phabricator.services.mozilla.com/D124702

dom/interfaces/base/nsIServiceWorkerManager.idl

@@ -216,6 +216,14 @@ interface nsIServiceWorkerManager : nsISupports
   [implicit_jscontext]
   Promise registerForAddonPrincipal(in nsIPrincipal aPrincipal);
 
+  /**
+   * Get an extension background service worker registration for a
+   * given extension principal, return an nsIServiceWorkerRegistrationInfo
+   * if one exists (or null if no registration has been found).
+   */
+  void getRegistrationForAddonPrincipal(in nsIPrincipal aPrincipal,
+                                        [optional, retval] out nsIServiceWorkerRegistrationInfo regInfo);
+
   /**
    * Unregister an existing ServiceWorker registration for `aScope`.
    * It keeps aCallback alive until the operation is concluded.

dom/serviceworkers/ServiceWorkerManager.cpp

@@ -2740,6 +2740,41 @@ ServiceWorkerManager::RegisterForAddonPrincipal(nsIPrincipal* aPrincipal,
   return NS_OK;
 }
 
+NS_IMETHODIMP
+ServiceWorkerManager::GetRegistrationForAddonPrincipal(
+    nsIPrincipal* aPrincipal, nsIServiceWorkerRegistrationInfo** aInfo) {
+  MOZ_ASSERT(aPrincipal);
+
+  MOZ_ASSERT(aPrincipal);
+  auto* addonPolicy = BasePrincipal::Cast(aPrincipal)->AddonPolicy();
+  if (!addonPolicy) {
+    return NS_ERROR_FAILURE;
+  }
+
+  nsCString scope;
+  auto result = addonPolicy->GetURL(u""_ns);
+  if (result.isOk()) {
+    scope.Assign(NS_ConvertUTF16toUTF8(result.unwrap()));
+  } else {
+    return NS_ERROR_FAILURE;
+  }
+
+  nsCOMPtr<nsIURI> scopeURI;
+  nsresult rv = NS_NewURI(getter_AddRefs(scopeURI), scope);
+  if (NS_FAILED(rv)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  RefPtr<ServiceWorkerRegistrationInfo> info =
+      GetServiceWorkerRegistrationInfo(aPrincipal, scopeURI);
+  if (!info) {
+    aInfo = nullptr;
+    return NS_OK;
+  }
+  info.forget(aInfo);
+  return NS_OK;
+}
+
 NS_IMETHODIMP
 ServiceWorkerManager::GetRegistrationByPrincipal(
     nsIPrincipal* aPrincipal, const nsAString& aScope,