Add a legacy sessions build config

Author: tejasd

firebase-perf/firebase-perf.gradle

@@ -70,13 +70,15 @@ android {
         buildConfigField("String", "TRANSPORT_LOG_SRC", "String.valueOf(\"FIREPERF\")")
         buildConfigField("Boolean", "ENFORCE_DEFAULT_LOG_SRC", "Boolean.valueOf(false)")
         buildConfigField("String", "FIREPERF_VERSION_NAME", "String.valueOf(\"" + property("version") + "\")")
+        buildConfigField("Boolean", "ENFORCE_LEGACY_SESSIONS", "Boolean.valueOf(false)")
 
         if (project.hasProperty("fireperfBuildForAutopush")) {
             // This allows the SDK to be built for "Autopush" env when the mentioned flag
             // (-PfireperfBuildForAutopush) is passed in the gradle build command (of either the
             // SDK or the Test App).
             buildConfigField("String", "TRANSPORT_LOG_SRC", "String.valueOf(\"FIREPERF_AUTOPUSH\")")
             buildConfigField("Boolean", "ENFORCE_DEFAULT_LOG_SRC", "Boolean.valueOf(true)")
+            buildConfigField("Boolean", "ENFORCE_LEGACY_SESSIONS", "Boolean.valueOf(true)")
         }
 
         minSdkVersion project.minSdkVersion

firebase-perf/src/main/java/com/google/firebase/perf/FirebasePerformance.java

@@ -44,7 +44,6 @@
 import com.google.firebase.perf.util.ImmutableBundle;
 import com.google.firebase.perf.util.Timer;
 import com.google.firebase.remoteconfig.RemoteConfigComponent;
-import com.google.firebase.sessions.BuildConfig;
 import com.google.firebase.sessions.api.FirebaseSessionsDependencies;
 import com.google.firebase.sessions.api.SessionSubscriber;
 import java.lang.annotation.Retention;
@@ -175,7 +174,7 @@ public static FirebasePerformance getInstance() {
       this.sessionSubscriber = new FirebasePerformanceSessionSubscriber(false);
       return;
     }
-    DebugEnforcementCheck.setEnforcement(BuildConfig.DEBUG);
+    DebugEnforcementCheck.setEnforcement(BuildConfig.ENFORCE_LEGACY_SESSIONS);
 
     TransportManager.getInstance()
         .initialize(firebaseApp, firebaseInstallationsApi, transportFactoryProvider);