[Ongoing Call] Always unregister the UidObserver.

Test: atest OngoingCallControllerTest
Fixes: 194731244
Change-Id: I39d20313f78ec0c632dcde999abc0057141bac64

packages/SystemUI/src/com/android/systemui/statusbar/phone/ongoingcall/OngoingCallController.kt

@@ -218,6 +218,10 @@ class OngoingCallController @Inject constructor(
         isCallAppVisible = isProcessVisibleToUser(
                 iActivityManager.getUidProcessState(currentCallNotificationInfo.uid, null))
 
+        if (uidObserver != null) {
+            iActivityManager.unregisterUidObserver(uidObserver)
+        }
+
         uidObserver = object : IUidObserver.Stub() {
             override fun onUidStateChanged(
                     uid: Int, procState: Int, procStateSeq: Long, capability: Int) {

packages/SystemUI/tests/src/com/android/systemui/statusbar/phone/ongoingcall/OngoingCallControllerTest.kt

@@ -184,6 +184,21 @@ class OngoingCallControllerTest : SysuiTestCase() {
                 .isGreaterThan(0)
     }
 
+    /** Regression test for b/194731244. */
+    @Test
+    fun onEntryUpdated_calledManyTimes_uidObserverUnregisteredManyTimes() {
+        val numCalls = 4
+
+        for (i in 0 until numCalls) {
+            // Re-create the notification each time so that it's considered a different object and
+            // observers will get re-registered (and hopefully unregistered).
+            notifCollectionListener.onEntryUpdated(createOngoingCallNotifEntry())
+        }
+
+        // There should be 1 observer still registered, so we should unregister n-1 times.
+        verify(mockIActivityManager, times(numCalls - 1)).unregisterUidObserver(any())
+    }
+
     /**
      * If a call notification is never added before #onEntryRemoved is called, then the listener
      * should never be notified.