remove .INSTANCE

Author: tejasd

firebase-perf/src/test/java/com/google/firebase/perf/session/gauges/GaugeManagerTest.java

@@ -335,7 +335,7 @@ public void testGaugeCounterStartsAJobToConsumeTheGeneratedMetrics() throws Inte
     PerfSession fakeSession = createTestSession(1);
     testGaugeManager.setApplicationProcessState(ApplicationProcessState.FOREGROUND);
     testGaugeManager.startCollectingGauges(fakeSession);
-    GaugeCounter.INSTANCE.setGaugeManager(testGaugeManager);
+    GaugeCounter.setGaugeManager(testGaugeManager);
 
     // There's no job to log the gauges.
     assertThat(fakeScheduledExecutorService.isEmpty()).isTrue();
@@ -377,7 +377,7 @@ public void testUpdateAppStateHandlesMultipleAppStates() {
     fakeSession.setGaugeAndEventCollectionEnabled(true);
     testGaugeManager.setApplicationProcessState(ApplicationProcessState.FOREGROUND);
     testGaugeManager.startCollectingGauges(fakeSession);
-    GaugeCounter.INSTANCE.setGaugeManager(testGaugeManager);
+    GaugeCounter.setGaugeManager(testGaugeManager);
 
     // Generate metrics that don't exceed the GaugeCounter.MAX_COUNT.
     generateMetricsAndIncrementCounter(10);