Fix potential null error in clearEvents.

* This is follow up from previous patch to fix an unresolved
comment.

* We're still changing the clearEvents mechanic to not null the list but
actually clear the list of events. We also change when the
flush->clearEvents call happen during the destroy process so it occurs
on the handlerThread when each session does its own cleanup.

Bug: 185162720
Test: atest CtsContentCaptureServiceTestCases
Change-Id: Ide5490903deec8c4bc8aae5dc76b1fadca29dbd0

2 files changed, 13 insertions, 9 deletions

diff --git a/core/java/android/view/contentcapture/ContentCaptureSession.java b/core/java/android/view/contentcapture/ContentCaptureSession.java
index c6332686bf7f..cc47f09d4e8d 100644
--- a/core/java/android/view/contentcapture/ContentCaptureSession.java
+++ b/core/java/android/view/contentcapture/ContentCaptureSession.java
@@ -341,11 +341,7 @@ public abstract class ContentCaptureSession implements AutoCloseable {
             }
         }
 
-        try {
-            flush(FLUSH_REASON_SESSION_FINISHED);
-        } finally {
-            onDestroy();
-        }
+        onDestroy();
     }
 
     abstract void onDestroy();
diff --git a/core/java/android/view/contentcapture/MainContentCaptureSession.java b/core/java/android/view/contentcapture/MainContentCaptureSession.java
index d8ac779ddc27..bcb914208958 100644
--- a/core/java/android/view/contentcapture/MainContentCaptureSession.java
+++ b/core/java/android/view/contentcapture/MainContentCaptureSession.java
@@ -263,7 +263,13 @@ public final class MainContentCaptureSession extends ContentCaptureSession {
     @Override
     void onDestroy() {
         mHandler.removeMessages(MSG_FLUSH);
-        mHandler.post(() -> destroySession());
+        mHandler.post(() -> {
+            try {
+                flush(FLUSH_REASON_SESSION_FINISHED);
+            } finally {
+                destroySession();
+            }
+        });
     }
 
     /**
@@ -571,9 +577,11 @@ public final class MainContentCaptureSession extends ContentCaptureSession {
     private ParceledListSlice<ContentCaptureEvent> clearEvents() {
         // NOTE: we must save a reference to the current mEvents and then set it to to null,
         // otherwise clearing it would clear it in the receiving side if the service is also local.
-        final List<ContentCaptureEvent> events = mEvents == null
-                ? Collections.EMPTY_LIST
-                : new ArrayList<>(mEvents);
+        if (mEvents == null) {
+            return new ParceledListSlice<>(Collections.EMPTY_LIST);
+        }
+
+        final List<ContentCaptureEvent> events = new ArrayList<>(mEvents);
         mEvents.clear();
         return new ParceledListSlice<>(events);
     }