Avoid memcpy in JavaToNativeEncodedImage

Followup to https://webrtc-review.googlesource.com/c/src/+/142160

Bug: webrtc:9378
Change-Id: If790cd628433046d6819a92449fcc68106535df4
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/154561
Reviewed-by: Sami Kalliomäki <sakal@webrtc.org>
Commit-Queue: Niels Moller <nisse@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#29359}
diff --git a/sdk/android/api/org/webrtc/EncodedImage.java b/sdk/android/api/org/webrtc/EncodedImage.java
index 682d9c4..fabf36a 100644
--- a/sdk/android/api/org/webrtc/EncodedImage.java
+++ b/sdk/android/api/org/webrtc/EncodedImage.java
@@ -71,6 +71,7 @@
 
   // A false return value means that the encoder expects that the buffer is no longer used after
   // VideoEncoder.Callback.onEncodedFrame returns.
+  @CalledByNative
   boolean maybeRetain() {
     if (supportsRetain) {
       retain();