media: VideoEncoderTest: fix bug introduced when setting input buffer size

prior CL removed a critical line.

Bug: 18921559

Change-Id: Ib7c702ebcf3427a67149c7336434c8791d4d39c7
diff --git a/tests/tests/media/src/android/media/cts/VideoEncoderTest.java b/tests/tests/media/src/android/media/cts/VideoEncoderTest.java
index 7b777a2..b275232 100644
--- a/tests/tests/media/src/android/media/cts/VideoEncoderTest.java
+++ b/tests/tests/media/src/android/media/cts/VideoEncoderTest.java
@@ -74,6 +74,7 @@
 
         public void addBuffer(ByteBuffer buffer, BufferInfo info) {
             ByteBuffer savedBuffer = ByteBuffer.allocate(info.size);
+            savedBuffer.put(buffer);
             if (info.size > mInputBufferSize) {
                 mInputBufferSize = info.size;
             }