[perf] make initialize & get singleton lines more explicit for vNext (#229)

Author: rachelsaunders

perf-next/index.js

@@ -13,18 +13,18 @@ function intialize() {
 
   // [START perf_initialize_app]
   // TODO: Replace the following with your app's Firebase project configuration
-  // See: https://firebase.google.com/docs/web/setup#config-object
+  // See: https://firebase.google.com/docs/web/learn-more#config-object
   const firebaseConfig = {
     // ...
   };
 
   // Initialize Firebase
-  initializeApp(firebaseConfig);
+  const app = initializeApp(firebaseConfig);
   // [END perf_initialize_app]
 
   // [START perf_singleton]
   // Initialize Performance Monitoring and get a reference to the service
-  const perf = getPerformance();
+  const perf = getPerformance(app);
   // [END perf_singleton]
 }
 

perf/index.js

@@ -10,7 +10,7 @@ const perf = firebase.performance();
 function intialize() {
   // [START perf_initialize_app]
   // TODO: Replace the following with your app's Firebase project configuration
-  // See: https://firebase.google.com/docs/web/setup#config-object
+  // See: https://firebase.google.com/docs/web/learn-more#config-object
   const firebaseConfig = {
     // ...
   };

snippets/perf-next/index/perf_initialize_app.js

@@ -6,11 +6,11 @@
 
 // [START perf_initialize_app_modular]
 // TODO: Replace the following with your app's Firebase project configuration
-// See: https://firebase.google.com/docs/web/setup#config-object
+// See: https://firebase.google.com/docs/web/learn-more#config-object
 const firebaseConfig = {
   // ...
 };
 
 // Initialize Firebase
-initializeApp(firebaseConfig);
+const app = initializeApp(firebaseConfig);
 // [END perf_initialize_app_modular]

snippets/perf-next/index/perf_singleton.js

@@ -6,5 +6,5 @@
 
 // [START perf_singleton_modular]
 // Initialize Performance Monitoring and get a reference to the service
-const perf = getPerformance();
+const perf = getPerformance(app);
 // [END perf_singleton_modular]