Add snippets for custom dependencies doc (#243)

* Snippets for custom dependencies doc

* Add app dependency

Author: sam-gc

auth-next/custom-dependencies.js

@@ -0,0 +1,58 @@
+// [SNIPPET_REGISTRY disabled]
+// [SNIPPETS_SEPARATION enabled]
+
+// Docs: https://source.corp.google.com/piper///depot/google3/third_party/devsite/firebase/en/docs/auth/web/custom-dependencies.md
+
+function getAuthEquivalent() {
+  // [START auth_get_auth_equivalent]
+  const {initializeAuth, browserLocalPersistence, browserPopupRedirectResolver, browserSessionPersistence, indexedDBLocalPersistence} = require("firebase/auth");
+  const {initializeApp} = require("firebase/app");
+
+  const app = initializeApp({/** Your app config */});
+  const auth = initializeAuth(app, {
+    persistence: [indexedDBLocalPersistence, browserLocalPersistence, browserSessionPersistence],
+    popupRedirectResolver: browserPopupRedirectResolver,
+  });
+  // [END auth_get_auth_equivalent]
+}
+
+function onlyBrowserLocal() {
+  // [START auth_only_browser_local]
+  const {initializeAuth, browserLocalPersistence} = require("firebase/auth");
+  const {initializeApp} = require("firebase/app");
+
+  const app = initializeApp({/** Your app config */});
+  const auth = initializeAuth(app, {
+    persistence: browserLocalPersistence,
+    // No popupRedirectResolver defined
+  });
+  // [END auth_only_browser_local]
+}
+
+function onlyIndexedDB() {
+  // [START auth_only_indexed_db]
+  const {initializeAuth, indexedDBLocalPersistence} = require("firebase/auth");
+  const {initializeApp} = require("firebase/app");
+
+  const app = initializeApp({/** Your app config */});
+  const auth = initializeAuth(app, {
+    persistence: indexedDBLocalPersistence,
+    // No popupRedirectResolver defined
+  });
+  // [END auth_only_indexed_db]
+}
+
+function signInRedirectManualDeps() {
+  // [START auth_sign_in_redirect_manual_deps]
+  const {initializeAuth, browserLocalPersistence, browserPopupRedirectResolver, indexedDBLocalPersistence, signInWithRedirect, GoogleAuthProvider} = require("firebase/auth");
+  const {initializeApp} = require("firebase/app");
+
+  const app = initializeApp({/** Your app config */});
+  const auth = initializeAuth(app, {
+    persistence: [indexedDBLocalPersistence, browserLocalPersistence],
+  });
+
+  // Later
+  signInWithRedirect(auth, new GoogleAuthProvider(), browserPopupRedirectResolver);
+  // [END auth_sign_in_redirect_manual_deps]
+}

snippets/auth-next/custom-dependencies/auth_get_auth_equivalent.js

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+// This snippet file was generated by processing the source file:
+// ./auth-next/custom-dependencies.js
+//
+// To update the snippets in this file, edit the source and then run
+// 'npm run snippets'.
+
+// [START auth_get_auth_equivalent_modular]
+import {initializeAuth, browserLocalPersistence, browserPopupRedirectResolver, browserSessionPersistence, indexedDBLocalPersistence} from "firebase/auth";
+import {initializeApp} from "firebase/app";
+
+const app = initializeApp({/** Your app config */});
+const auth = initializeAuth(app, {
+  persistence: [indexedDBLocalPersistence, browserLocalPersistence, browserSessionPersistence],
+  popupRedirectResolver: browserPopupRedirectResolver,
+});
+// [END auth_get_auth_equivalent_modular]

snippets/auth-next/custom-dependencies/auth_only_browser_local.js

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+// This snippet file was generated by processing the source file:
+// ./auth-next/custom-dependencies.js
+//
+// To update the snippets in this file, edit the source and then run
+// 'npm run snippets'.
+
+// [START auth_only_browser_local_modular]
+import {initializeAuth, browserLocalPersistence} from "firebase/auth";
+import {initializeApp} from "firebase/app";
+
+const app = initializeApp({/** Your app config */});
+const auth = initializeAuth(app, {
+  persistence: browserLocalPersistence,
+  // No popupRedirectResolver defined
+});
+// [END auth_only_browser_local_modular]

snippets/auth-next/custom-dependencies/auth_only_indexed_db.js

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+// This snippet file was generated by processing the source file:
+// ./auth-next/custom-dependencies.js
+//
+// To update the snippets in this file, edit the source and then run
+// 'npm run snippets'.
+
+// [START auth_only_indexed_db_modular]
+import {initializeAuth, indexedDBLocalPersistence} from "firebase/auth";
+import {initializeApp} from "firebase/app";
+
+const app = initializeApp({/** Your app config */});
+const auth = initializeAuth(app, {
+  persistence: indexedDBLocalPersistence,
+  // No popupRedirectResolver defined
+});
+// [END auth_only_indexed_db_modular]

snippets/auth-next/custom-dependencies/auth_sign_in_redirect_manual_deps.js

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+// This snippet file was generated by processing the source file:
+// ./auth-next/custom-dependencies.js
+//
+// To update the snippets in this file, edit the source and then run
+// 'npm run snippets'.
+
+// [START auth_sign_in_redirect_manual_deps_modular]
+import {initializeAuth, browserLocalPersistence, browserPopupRedirectResolver, indexedDBLocalPersistence, signInWithRedirect, GoogleAuthProvider} from "firebase/auth";
+import {initializeApp} from "firebase/app";
+
+const app = initializeApp({/** Your app config */});
+const auth = initializeAuth(app, {
+  persistence: [indexedDBLocalPersistence, browserLocalPersistence],
+});
+
+// Later
+signInWithRedirect(auth, new GoogleAuthProvider(), browserPopupRedirectResolver);
+// [END auth_sign_in_redirect_manual_deps_modular]