DataSourceCallback: fix java docs

Test: make offline-sdk-docs
Bug: 112549021
Change-Id: I4c082f3e9547a768f9327cfaf874f3bba0dab8bf

media/java/android/media/DataSourceCallback.java

@@ -47,7 +47,7 @@ public abstract class DataSourceCallback implements Closeable {
      * @param offset the offset within buffer to read the data into.
      * @param size the number of bytes to read.
      * @throws IOException on fatal errors.
-     * @return the number of bytes read, or -1 if there was an error.
+     * @return the number of bytes read, or -1 if end of stream is reached.
      */
     public abstract int readAt(long position, byte[] buffer, int offset, int size)
             throws IOException;

media/java/android/media/MediaDataSource.java

@@ -46,7 +46,7 @@ public abstract class MediaDataSource implements Closeable {
      * @param offset the offset within buffer to read the data into.
      * @param size the number of bytes to read.
      * @throws IOException on fatal errors.
-     * @return the number of bytes read, or -1 if there was an error.
+     * @return the number of bytes read, or -1 if end of stream is reached.
      */
     public abstract int readAt(long position, byte[] buffer, int offset, int size)
             throws IOException;