nfc(api): Dont invoke enableReaderMode from setDiscoveryTech

Calling |enableReaderMode| prevents us from chaning the listen tech.

Bug: 337291737
Test: atest CtsNfcHceMultiDeviceTestCases
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:c1eec317f5d98181e7ef8826a16c96ebebd9d498)
Merged-In: Id6a5e865cd69bafcf2e0dcfafe104aee3330f138
Change-Id: Id6a5e865cd69bafcf2e0dcfafe104aee3330f138
diff --git a/nfc/java/android/nfc/NfcActivityManager.java b/nfc/java/android/nfc/NfcActivityManager.java
index f03fc0a..0e40db6 100644
--- a/nfc/java/android/nfc/NfcActivityManager.java
+++ b/nfc/java/android/nfc/NfcActivityManager.java
@@ -195,16 +195,25 @@
             Bundle extras) {
         boolean isResumed;
         Binder token;
+        int pollTech, listenTech;
         synchronized (NfcActivityManager.this) {
             NfcActivityState state = getActivityState(activity);
             state.readerCallback = callback;
             state.readerModeFlags = flags;
             state.readerModeExtras = extras;
+            pollTech = state.mPollTech;
+            listenTech = state.mListenTech;
             token = state.token;
             isResumed = state.resumed;
         }
         if (isResumed) {
-            setReaderMode(token, flags, extras);
+            if (listenTech != NfcAdapter.FLAG_USE_ALL_TECH
+                    || pollTech != NfcAdapter.FLAG_USE_ALL_TECH) {
+                throw new IllegalStateException(
+                    "Cannot be used when alternative DiscoveryTechnology is set");
+            } else {
+                setReaderMode(token, flags, extras);
+            }
         }
     }
 
@@ -385,15 +394,12 @@
         boolean readerModeFlagsSet;
         synchronized (NfcActivityManager.this) {
             NfcActivityState state = getActivityState(activity);
-            readerModeFlagsSet = state.readerModeFlags != 0;
             state.mListenTech = NfcAdapter.FLAG_USE_ALL_TECH;
             state.mPollTech = NfcAdapter.FLAG_USE_ALL_TECH;
             token = state.token;
             isResumed = state.resumed;
         }
-        if (readerModeFlagsSet) {
-            disableReaderMode(activity);
-        } else if (isResumed) {
+        if (isResumed) {
             changeDiscoveryTech(token, NfcAdapter.FLAG_USE_ALL_TECH, NfcAdapter.FLAG_USE_ALL_TECH);
         }