Remove event listeners when touch session ends

Currently, the event listeners may still run after the touch session has
ended, which is causing NullPointerException to be thrown

Was able to reproduce this by forcing dreams to switch while swiping up
on the screen to bring up the bouncer.

Bug: 275659024
Test: atest DreamOverlayTouchMonitorTest
Change-Id: I2e47d16231e0f7297e4e7781325a6de9f8e8c948

2 files changed, 33 insertions, 1 deletions

diff --git a/packages/SystemUI/src/com/android/systemui/dreams/touch/DreamOverlayTouchMonitor.java b/packages/SystemUI/src/com/android/systemui/dreams/touch/DreamOverlayTouchMonitor.java
index 7f44463f1191..aca621bd9e55 100644
--- a/packages/SystemUI/src/com/android/systemui/dreams/touch/DreamOverlayTouchMonitor.java
+++ b/packages/SystemUI/src/com/android/systemui/dreams/touch/DreamOverlayTouchMonitor.java
@@ -41,6 +41,7 @@ import com.google.common.util.concurrent.ListenableFuture;
 import java.util.Collection;
 import java.util.HashMap;
 import java.util.HashSet;
+import java.util.Iterator;
 import java.util.Set;
 import java.util.concurrent.Executor;
 import java.util.function.Consumer;
@@ -195,7 +196,14 @@ public class DreamOverlayTouchMonitor {
          * Called by the monitor when this session is removed.
          */
         private void onRemoved() {
-            mCallbacks.forEach(callback -> callback.onRemoved());
+            mEventListeners.clear();
+            mGestureListeners.clear();
+            final Iterator<Callback> iter = mCallbacks.iterator();
+            while (iter.hasNext()) {
+                final Callback callback = iter.next();
+                callback.onRemoved();
+                iter.remove();
+            }
         }
 
         @Override
diff --git a/packages/SystemUI/tests/src/com/android/systemui/dreams/touch/DreamOverlayTouchMonitorTest.java b/packages/SystemUI/tests/src/com/android/systemui/dreams/touch/DreamOverlayTouchMonitorTest.java
index 08427dab978b..21397d97b578 100644
--- a/packages/SystemUI/tests/src/com/android/systemui/dreams/touch/DreamOverlayTouchMonitorTest.java
+++ b/packages/SystemUI/tests/src/com/android/systemui/dreams/touch/DreamOverlayTouchMonitorTest.java
@@ -269,6 +269,30 @@ public class DreamOverlayTouchMonitorTest extends SysuiTestCase {
     }
 
     @Test
+    public void testInputEventPropagationAfterRemoval() {
+        final DreamTouchHandler touchHandler = Mockito.mock(DreamTouchHandler.class);
+
+        final Environment environment = new Environment(Stream.of(touchHandler)
+                .collect(Collectors.toCollection(HashSet::new)));
+
+        final InputEvent initialEvent = Mockito.mock(InputEvent.class);
+        environment.publishInputEvent(initialEvent);
+
+        // Ensure session started
+        final DreamTouchHandler.TouchSession session = captureSession(touchHandler);
+        final InputChannelCompat.InputEventListener eventListener =
+                registerInputEventListener(session);
+
+        session.pop();
+        environment.executeAll();
+
+        final InputEvent event = Mockito.mock(InputEvent.class);
+        environment.publishInputEvent(event);
+
+        verify(eventListener, never()).onInputEvent(eq(event));
+    }
+
+    @Test
     public void testInputGesturePropagation() {
         final DreamTouchHandler touchHandler = Mockito.mock(DreamTouchHandler.class);