Merge "IBinder.transact: clarify return" am: 2794ff0ca8 am: 5e19eaf0e8 am: 83de9444cb

Original change: https://android-review.googlesource.com/c/platform/frameworks/base/+/1990775

Change-Id: Ia92f237101e5e930100a5723651602c7298ac0d9

core/java/android/os/IBinder.java

@@ -293,7 +293,10 @@ public interface IBinder {
      *
      * @return Returns the result from {@link Binder#onTransact}.  A successful call
      * generally returns true; false generally means the transaction code was not
-     * understood.
+     * understood.  For a oneway call to a different process false should never be
+     * returned.  If a oneway call is made to code in the same process (usually to
+     * a C++ or Rust implementation), then there are no oneway semantics, and
+     * false can still be returned.
      */
     public boolean transact(int code, @NonNull Parcel data, @Nullable Parcel reply, int flags)
         throws RemoteException;