Switch to usage of AQS instead of sessions in most places

Author: tejasd

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

@@ -21,7 +21,6 @@
 import com.google.firebase.perf.application.AppStateMonitor;
 import com.google.firebase.perf.config.ConfigResolver;
 import com.google.firebase.perf.metrics.AppStartTrace;
-import com.google.firebase.perf.session.SessionManager;
 import java.util.concurrent.Executor;
 
 /**
@@ -50,13 +49,5 @@ public FirebasePerfEarly(
       appStartTrace.registerActivityLifecycleCallbacks(context);
       uiExecutor.execute(new AppStartTrace.StartFromBackgroundRunnable(appStartTrace));
     }
-
-    // TODO: Bring back Firebase Sessions dependency to watch for updates to sessions.
-
-    // In the case of cold start, we create a session and start collecting gauges as early as
-    // possible.
-    // There is code in SessionManager that prevents us from resetting the session twice in case
-    // of app cold start.
-    SessionManager.getInstance().initializeGaugeCollection();
   }
 }

firebase-perf/src/main/java/com/google/firebase/perf/session/FirebasePerformanceSessionSubscriber.kt

@@ -34,6 +34,8 @@ class FirebasePerformanceSessionSubscriber(override val isDataCollectionEnabled:
       currentPerfSession.setAQSId(sessionDetails)
       GaugeManager.getInstance()
         .logGaugeMetadata(currentPerfSession.aqsSessionId(), ApplicationProcessState.FOREGROUND)
+      // TODO(b/394127311): Explore deciding whether to collect gauges or not via. AQS.
+      SessionManager.getInstance().initializeGaugeCollection()
       return
     }
 

firebase-perf/src/main/java/com/google/firebase/perf/session/gauges/GaugeManager.java

@@ -59,8 +59,9 @@ public class GaugeManager {
   private final TransportManager transportManager;
 
   @Nullable private GaugeMetadataManager gaugeMetadataManager;
-  @Nullable private ScheduledFuture gaugeManagerDataCollectionJob = null;
+  @Nullable private ScheduledFuture<?> gaugeManagerDataCollectionJob = null;
   @Nullable private String sessionId = null;
+  @Nullable private String aqsSessionId = null;
   private ApplicationProcessState applicationProcessState =
       ApplicationProcessState.APPLICATION_PROCESS_STATE_UNKNOWN;
 
@@ -130,10 +131,11 @@ public void startCollectingGauges(
     }
 
     this.sessionId = session.sessionId();
+    this.aqsSessionId = session.aqsSessionId();
     this.applicationProcessState = applicationProcessState;
 
     // This is needed, otherwise the Runnable might use a stale value.
-    final String sessionIdForScheduledTask = sessionId;
+    final String sessionIdForScheduledTask = aqsSessionId;
     final ApplicationProcessState applicationProcessStateForScheduledTask = applicationProcessState;
 
     // TODO(b/394127311): Switch to using AQS.
@@ -195,7 +197,7 @@ public void stopCollectingGauges() {
     }
 
     // This is needed, otherwise the Runnable might use a stale value.
-    final String sessionIdForScheduledTask = sessionId;
+    final String sessionIdForScheduledTask = aqsSessionId;
     final ApplicationProcessState applicationProcessStateForScheduledTask = applicationProcessState;
 
     cpuGaugeCollector.get().stopCollecting();
@@ -205,10 +207,9 @@ public void stopCollectingGauges() {
       gaugeManagerDataCollectionJob.cancel(false);
     }
 
-    // TODO(b/394127311): Switch to using AQS.
     // Flush any data that was collected for this session one last time.
     @SuppressWarnings("FutureReturnValueIgnored")
-    ScheduledFuture unusedFuture =
+    ScheduledFuture<?> unusedFuture =
         gaugeManagerExecutor
             .get()
             .schedule(