Using LaunchActivity when possible

... to prevent race

In [1], we store ActivityClientRecord earlier to make
ActivityClientRecord accessible in onCreate Lifcycle callback.
However, we still store the activity after Activity#onCreate.

This CL fixes the exception by obtaining ActivityClientRecord
from launch Activity list first to prevent race.

fixes: 196900007
Test: Try reproducible steps several times and didn't see
the error log.

[1]: 85986bf974

Change-Id: I7553c56cad474feb73fca73c72b5e6e833b46fbf

core/java/android/app/servertransaction/ActivityTransactionItem.java

@@ -59,36 +59,37 @@ public abstract class ActivityTransactionItem extends ClientTransactionItem {
     }
 
     /**
-     * Get the {@link ActivityClientRecord} instance that corresponds to the provided token.
+     * Gets the {@link ActivityClientRecord} instance that corresponds to the provided token.
      * @param client Target client handler.
      * @param token Target activity token.
-     * @param includeLaunching Indicate to also find the {@link ActivityClientRecord} in launching
-     *                         activity list. It should be noted that there is no activity in
+     * @param includeLaunching Indicate to find the {@link ActivityClientRecord} in launching
+     *                         activity list.
+     *                         <p>Note that there is no {@link android.app.Activity} instance in
      *                         {@link ActivityClientRecord} from the launching activity list.
      * @return The {@link ActivityClientRecord} instance that corresponds to the provided token.
      */
     @NonNull ActivityClientRecord getActivityClientRecord(
             @NonNull ClientTransactionHandler client, IBinder token, boolean includeLaunching) {
-        ActivityClientRecord r = client.getActivityClient(token);
-        if (r != null) {
-            if (client.getActivity(token) == null) {
+        ActivityClientRecord r = null;
+        // Check launching Activity first to prevent race condition that activity instance has not
+        // yet set to ActivityClientRecord.
+        if (includeLaunching) {
+            r = client.getLaunchingActivity(token);
+        }
+        // Then if we don't want to find launching Activity or the ActivityClientRecord doesn't
+        // exist in launching Activity list. The ActivityClientRecord should have been initialized
+        // and put in the Activity list.
+        if (r == null) {
+            r = client.getActivityClient(token);
+            if (r != null && client.getActivity(token) == null) {
                 throw new IllegalArgumentException("Activity must not be null to execute "
                         + "transaction item");
             }
-            return r;
-        }
-        // The activity may not be launched yet. Fallback to check launching activity.
-        if (includeLaunching) {
-            r = client.getLaunchingActivity(token);
         }
         if (r == null) {
             throw new IllegalArgumentException("Activity client record must not be null to execute "
                     + "transaction item");
         }
-
-        // We don't need to check the activity of launching activity client records because they
-        // have not been launched yet.
-
         return r;
     }
 }