Add trace module to Android

android/app/build.gradle

@@ -234,6 +234,9 @@ dependencies {
         implementation jscFlavor
     }
 
+    implementation platform("com.google.firebase:firebase-bom:20.0.2")
+    implementation "com.google.firebase:firebase-perf"
+
     // GIF support
     implementation 'com.facebook.fresco:fresco:2.3.0'
     implementation 'com.facebook.fresco:animated-gif:2.3.0'

android/app/src/debug/AndroidManifest.xml

@@ -4,5 +4,10 @@
 
     <uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW"/>
     <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
-    <application android:usesCleartextTraffic="true" tools:targetApi="28" tools:ignore="GoogleAppIndexingWarning" />
+    <application android:usesCleartextTraffic="true" tools:targetApi="28" tools:ignore="GoogleAppIndexingWarning">
+        <meta-data
+            android:name="firebase_performance_logcat_enabled"
+            android:value="true"
+        />
+    </application>
 </manifest>

android/app/src/main/java/com/expensify/chat/ExpensifyAppPackage.java

@@ -0,0 +1,29 @@
+package com.expensify.chat;
+
+import com.facebook.react.ReactPackage;
+import com.facebook.react.bridge.NativeModule;
+import com.facebook.react.bridge.ReactApplicationContext;
+import com.facebook.react.uimanager.ViewManager;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+public class ExpensifyAppPackage implements ReactPackage {
+
+    @Override
+    public List<ViewManager> createViewManagers(ReactApplicationContext reactContext) {
+        return Collections.emptyList();
+    }
+
+    @Override
+    public List<NativeModule> createNativeModules(
+            ReactApplicationContext reactContext) {
+        List<NativeModule> modules = new ArrayList<>();
+
+        modules.add(new StartupTimer(reactContext));
+
+        return modules;
+    }
+
+}

android/app/src/main/java/com/expensify/chat/MainApplication.java

@@ -42,6 +42,7 @@ protected List<ReactPackage> getPackages() {
           // Packages that cannot be autolinked yet can be added manually here, for example:
           // packages.add(new MyReactNativePackage());
           packages.add(new PlaidPackage());
+          packages.add(new ExpensifyAppPackage());
 
           // Add unimodules
           List<ReactPackage> unimodules = Arrays.<ReactPackage>asList(
@@ -76,6 +77,9 @@ public void onCreate() {
           FirebaseCrashlytics.getInstance().setCrashlyticsCollectionEnabled(false);
       }
 
+      // Start the startup timer
+      StartupTimer.start();
+
       // Increase SQLite DB write size
       try {
         Field field = CursorWindow.class.getDeclaredField("sCursorWindowSize");

android/app/src/main/java/com/expensify/chat/StartupTimer.java

@@ -0,0 +1,33 @@
+package com.expensify.chat;
+import com.facebook.react.bridge.ReactApplicationContext;
+import com.facebook.react.bridge.ReactContextBaseJavaModule;
+import com.facebook.react.bridge.ReactMethod;
+import com.google.firebase.perf.FirebasePerformance;
+import com.google.firebase.perf.metrics.Trace;
+
+public class StartupTimer extends ReactContextBaseJavaModule {
+    StartupTimer(ReactApplicationContext context) {
+        super(context);
+    }
+
+    private static Trace trace = null;
+
+    @Override
+    public String getName() {
+        return "StartupTimer";
+    }
+
+    @ReactMethod
+    public void stop() {
+        if (trace == null) {
+            return;
+        }
+
+        trace.stop();
+    }
+
+    public static void start() {
+        trace = FirebasePerformance.getInstance().newTrace("js_loaded");
+        trace.start();
+    }
+}