Add validation for checking if a Screen Trace has non-positive totalFrames (#2944)

* Add validation to ensure screen traces must have positive totalFrames before being sent to backend

Author: leotianlizhan

firebase-perf/src/main/java/com/google/firebase/perf/metrics/validator/FirebasePerfTraceValidator.java

@@ -104,6 +104,15 @@ private boolean areCountersValid(@Nullable TraceMetric trace, int deep) {
     return true;
   }
 
+  private boolean isScreenTrace(@NonNull TraceMetric trace) {
+    return trace.getName().startsWith(Constants.SCREEN_TRACE_PREFIX);
+  }
+
+  private boolean isValidScreenTrace(@NonNull TraceMetric trace) {
+    Long totalFrames = trace.getCountersMap().get(Constants.CounterNames.FRAMES_TOTAL.toString());
+    return totalFrames != null && totalFrames.compareTo(0L) > 0;
+  }
+
   private boolean isValidTrace(@Nullable TraceMetric trace, int deep) {
     if (trace == null) {
       logger.warn("TraceMetric is null");
@@ -126,6 +135,10 @@ private boolean isValidTrace(@Nullable TraceMetric trace, int deep) {
       logger.warn("clientStartTimeUs is null.");
       return false;
     }
+    if (isScreenTrace(trace) && !isValidScreenTrace(trace)) {
+      logger.warn("non-positive totalFrames in screen trace " + trace.getName());
+      return false;
+    }
     for (TraceMetric subtrace : trace.getSubtracesList()) {
       if (!isValidTrace(subtrace, deep + 1)) {
         return false;

firebase-perf/src/test/java/com/google/firebase/perf/metrics/validator/FirebasePerfTraceValidatorTest.java

@@ -159,6 +159,15 @@ public void testInvalidCounterSubtrace() {
     assertThat(new FirebasePerfTraceValidator(trace.build()).isValidPerfMetric()).isFalse();
   }
 
+  @Test
+  public void screenTrace_shouldNotAllowNonPositiveTotalFrames() {
+    TraceMetric.Builder trace =
+        createValidTraceMetric().setName(Constants.SCREEN_TRACE_PREFIX + "TestActivity");
+    assertThat(new FirebasePerfTraceValidator(trace.build()).isValidPerfMetric()).isFalse();
+    trace.putCounters(Constants.CounterNames.FRAMES_TOTAL.toString(), 0L);
+    assertThat(new FirebasePerfTraceValidator(trace.build()).isValidPerfMetric()).isFalse();
+  }
+
   @Test
   public void testInvalidCustomAttribute() {
     TraceMetric.Builder trace = createValidTraceMetric().putCustomAttributes("_test", "value");