better readability

Author: leotianlizhan

firebase-perf/src/main/java/com/google/firebase/perf/metrics/AppStartTrace.java

@@ -212,7 +212,6 @@ private void recordFirstDrawDone() {
     }
     Timer start = getStartTimer();
     this.firstDrawDone = clock.getTime();
-    int subtraceCount = this.experimentTtid.getSubtracesCount();
     this.experimentTtid
         .setClientStartTimeUs(start.getMicros())
         .setDurationUs(start.getDurationMicros(this.firstDrawDone));
@@ -234,7 +233,7 @@ private void recordFirstDrawDone() {
 
     this.experimentTtid.addPerfSessions(this.startSession.build());
 
-    if (subtraceCount > 0) {
+    if (isExperimentTraceDone()) {
       executorService.execute(() -> this.logExperimentTtid(this.experimentTtid));
 
       if (isRegisteredForLifecycleCallbacks) {
@@ -250,7 +249,6 @@ private void recordFirstDrawDonePreDraw() {
     }
     Timer start = getStartTimer();
     this.preDraw = clock.getTime();
-    int subtraceCount = this.experimentTtid.getSubtracesCount();
     TraceMetric.Builder subtrace =
         TraceMetric.newBuilder()
             .setName("_experiment_preDraw")
@@ -265,7 +263,7 @@ private void recordFirstDrawDonePreDraw() {
         .setDurationUs(start.getDurationUptimeMicros(this.preDraw));
     this.experimentTtid.addSubtraces(subtrace.build());
 
-    if (subtraceCount > 0) {
+    if (isExperimentTraceDone()) {
       executorService.execute(() -> this.logExperimentTtid(this.experimentTtid));
 
       if (isRegisteredForLifecycleCallbacks) {
@@ -275,6 +273,10 @@ private void recordFirstDrawDonePreDraw() {
     }
   }
 
+  private boolean isExperimentTraceDone() {
+    return this.preDraw != null && this.firstDrawDone != null;
+  }
+
   @Override
   public synchronized void onActivityCreated(Activity activity, Bundle savedInstanceState) {
     if (isStartedFromBackground || onCreateTime != null // An activity already called onCreate()
@@ -385,7 +387,8 @@ public void onActivityPaused(Activity activity) {
       return;
     }
     Timer onPauseTime = clock.getTime();
-    TraceMetric.Builder subtrace = TraceMetric.newBuilder()
+    TraceMetric.Builder subtrace =
+        TraceMetric.newBuilder()
             .setName("_experiment_onPause")
             .setClientStartTimeUs(onPauseTime.getMicros())
             .setDurationUs(getStartTimer().getDurationMicros(onPauseTime));
@@ -398,7 +401,8 @@ public void onActivityStopped(Activity activity) {
       return;
     }
     Timer onStopTime = clock.getTime();
-    TraceMetric.Builder subtrace = TraceMetric.newBuilder()
+    TraceMetric.Builder subtrace =
+        TraceMetric.newBuilder()
             .setName("_experiment_onStop")
             .setClientStartTimeUs(onStopTime.getMicros())
             .setDurationUs(getStartTimer().getDurationMicros(onStopTime));

firebase-perf/src/main/java/com/google/firebase/perf/util/FirstDrawDoneListener.java

@@ -18,14 +18,12 @@
 import android.os.Looper;
 import android.view.View;
 import android.view.ViewTreeObserver;
-import androidx.annotation.RequiresApi;
 import java.util.concurrent.atomic.AtomicReference;
 
 /**
  * OnDrawListener that unregisters itself and invokes callback when the next draw is done. This API
  * 16+ implementation is an approximation of the initial-display-time defined by Android Vitals.
  */
-@RequiresApi(Build.VERSION_CODES.JELLY_BEAN)
 public class FirstDrawDoneListener implements ViewTreeObserver.OnDrawListener {
   private final Handler mainThreadHandler = new Handler(Looper.getMainLooper());
   private final AtomicReference<View> viewReference;

firebase-perf/src/main/java/com/google/firebase/perf/util/PreDrawListener.java

@@ -19,6 +19,10 @@
 import android.view.ViewTreeObserver;
 import java.util.concurrent.atomic.AtomicReference;
 
+/**
+ * OnPreDraw listener that unregisters itself and post a callback to the main thread during
+ * OnPreDraw. This is an approximation of the initial-display time defined by Android Vitals.
+ */
 public class PreDrawListener implements ViewTreeObserver.OnPreDrawListener {
   private final Handler mainThreadHandler = new Handler(Looper.getMainLooper());
   private final AtomicReference<View> viewReference;