Clean up Aes128DataSource.

library/src/main/java/com/google/android/exoplayer/hls/HlsChunkSource.java

@@ -474,7 +474,7 @@ public class HlsChunkSource {
     System.arraycopy(ivData, offset, ivDataWithPadding, ivDataWithPadding.length - ivData.length
         + offset, ivData.length - offset);
 
-    encryptedDataSource = new Aes128DataSource(secretKey, ivDataWithPadding, upstreamDataSource);
+    encryptedDataSource = new Aes128DataSource(upstreamDataSource, secretKey, ivDataWithPadding);
     encryptionKeyUri = keyUri;
     encryptedDataSourceIv = iv;
     encryptedDataSourceSecretKey = secretKey;

library/src/main/java/com/google/android/exoplayer/upstream/Aes128DataSource.java

@@ -34,20 +34,24 @@ import javax.crypto.spec.SecretKeySpec;
 /**
  * A {@link DataSource} that decrypts the data read from an upstream source, encrypted with AES-128
  * with a 128-bit key and PKCS7 padding.
- *
  */
 public class Aes128DataSource implements DataSource {
 
   private final DataSource upstream;
-  private final byte[] secretKey;
+  private final byte[] encryptionKey;
-  private final byte[] iv;
+  private final byte[] encryptionIv;
 
   private CipherInputStream cipherInputStream;
 
-  public Aes128DataSource(byte[] secretKey, byte[] iv, DataSource upstream) {
+  /**
+   * @param upstream The upstream {@link DataSource}.
+   * @param encryptionKey The encryption key.
+   * @param encryptionIv The encryption initialization vector.
+   */
+  public Aes128DataSource(DataSource upstream, byte[] encryptionKey, byte[] encryptionIv) {
     this.upstream = upstream;
-    this.secretKey = secretKey;
+    this.encryptionKey = encryptionKey;
-    this.iv = iv;
+    this.encryptionIv = encryptionIv;
   }
 
   @Override
@@ -61,8 +65,8 @@ public class Aes128DataSource implements DataSource {
       throw new RuntimeException(e);
     }
 
-    Key cipherKey = new SecretKeySpec(secretKey, "AES");
+    Key cipherKey = new SecretKeySpec(encryptionKey, "AES");
-    AlgorithmParameterSpec cipherIV = new IvParameterSpec(iv);
+    AlgorithmParameterSpec cipherIV = new IvParameterSpec(encryptionIv);
 
     try {
       cipher.init(Cipher.DECRYPT_MODE, cipherKey, cipherIV);

library/src/main/java/com/google/android/exoplayer/upstream/UnexpectedLengthException.java

@@ -20,6 +20,7 @@ import java.io.IOException;
 /**
  * Thrown when the length of some data does not match an expected length.
  */
+@Deprecated
 public final class UnexpectedLengthException extends IOException {
 
   /**