Promote getResponseHeaders to DataSource

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=199607604

extensions/cronet/src/main/java/com/google/android/exoplayer2/ext/cronet/CronetDataSource.java

@@ -32,6 +32,7 @@ import java.io.IOException;
 import java.net.SocketTimeoutException;
 import java.net.UnknownHostException;
 import java.nio.ByteBuffer;
+import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
@@ -247,7 +248,7 @@ public class CronetDataSource extends UrlRequest.Callback implements HttpDataSou
 
   @Override
   public Map<String, List<String>> getResponseHeaders() {
-    return responseInfo == null ? null : responseInfo.getAllHeaders();
+    return responseInfo == null ? Collections.emptyMap() : responseInfo.getAllHeaders();
   }
 
   @Override

extensions/okhttp/src/main/java/com/google/android/exoplayer2/ext/okhttp/OkHttpDataSource.java

@@ -30,6 +30,7 @@ import java.io.EOFException;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.InterruptedIOException;
+import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 import java.util.concurrent.atomic.AtomicReference;
@@ -131,7 +132,7 @@ public class OkHttpDataSource implements HttpDataSource {
 
   @Override
   public Map<String, List<String>> getResponseHeaders() {
-    return response == null ? null : response.headers().toMultimap();
+    return response == null ? Collections.emptyMap() : response.headers().toMultimap();
   }
 
   @Override

library/core/src/main/java/com/google/android/exoplayer2/upstream/DataSource.java

@@ -19,6 +19,9 @@ import android.net.Uri;
 import android.support.annotation.Nullable;
 import com.google.android.exoplayer2.C;
 import java.io.IOException;
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
 
 /**
  * A component from which streams of data can be read.
@@ -82,6 +85,14 @@ public interface DataSource {
    */
   @Nullable Uri getUri();
 
+  /**
+   * When the source is open, returns the response headers associated with the last {@link #open}
+   * call. Otherwise, returns an empty map.
+   */
+  default Map<String, List<String>> getResponseHeaders() {
+    return Collections.emptyMap();
+  }
+
   /**
    * Closes the source.
    * <p>

library/core/src/main/java/com/google/android/exoplayer2/upstream/DefaultDataSource.java

@@ -21,6 +21,8 @@ import android.util.Log;
 import com.google.android.exoplayer2.util.Assertions;
 import com.google.android.exoplayer2.util.Util;
 import java.io.IOException;
+import java.util.List;
+import java.util.Map;
 
 /**
  * A {@link DataSource} that supports multiple URI schemes. The supported schemes are:
@@ -157,6 +159,13 @@ public final class DefaultDataSource implements DataSource {
     return dataSource == null ? null : dataSource.getUri();
   }
 
+  @Override
+  public Map<String, List<String>> getResponseHeaders() {
+    return dataSource == null
+        ? DataSource.super.getResponseHeaders()
+        : dataSource.getResponseHeaders();
+  }
+
   @Override
   public void close() throws IOException {
     if (dataSource != null) {

library/core/src/main/java/com/google/android/exoplayer2/upstream/DefaultHttpDataSource.java

@@ -32,6 +32,7 @@ import java.net.HttpURLConnection;
 import java.net.NoRouteToHostException;
 import java.net.ProtocolException;
 import java.net.URL;
+import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 import java.util.concurrent.atomic.AtomicReference;
@@ -162,7 +163,7 @@ public class DefaultHttpDataSource implements HttpDataSource {
 
   @Override
   public Map<String, List<String>> getResponseHeaders() {
-    return connection == null ? null : connection.getHeaderFields();
+    return connection == null ? Collections.emptyMap() : connection.getHeaderFields();
   }
 
   @Override

library/core/src/main/java/com/google/android/exoplayer2/upstream/HttpDataSource.java

@@ -341,10 +341,6 @@ public interface HttpDataSource extends DataSource {
    */
   void clearAllRequestProperties();
 
-  /**
+  @Override
-   * Returns the headers provided in the response, or {@code null} if response headers are
-   * unavailable.
-   */
   Map<String, List<String>> getResponseHeaders();
-
 }

library/core/src/main/java/com/google/android/exoplayer2/upstream/cache/CacheDataSource.java

@@ -31,6 +31,8 @@ import java.io.IOException;
 import java.io.InterruptedIOException;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
+import java.util.List;
+import java.util.Map;
 
 /**
  * A {@link DataSource} that reads and writes a {@link Cache}. Requests are fulfilled from the cache
@@ -332,6 +334,14 @@ public final class CacheDataSource implements DataSource {
     return actualUri;
   }
 
+  @Override
+  public Map<String, List<String>> getResponseHeaders() {
+    // TODO: Implement.
+    return isReadingFromUpstream()
+        ? upstreamDataSource.getResponseHeaders()
+        : DataSource.super.getResponseHeaders();
+  }
+
   @Override
   public void close() throws IOException {
     uri = null;

library/core/src/main/java/com/google/android/exoplayer2/upstream/crypto/AesCipherDataSource.java

@@ -20,6 +20,8 @@ import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.upstream.DataSource;
 import com.google.android.exoplayer2.upstream.DataSpec;
 import java.io.IOException;
+import java.util.List;
+import java.util.Map;
 import javax.crypto.Cipher;
 
 /**
@@ -59,15 +61,19 @@ public final class AesCipherDataSource implements DataSource {
     return read;
   }
 
-  @Override
-  public void close() throws IOException {
-    cipher = null;
-    upstream.close();
-  }
-
   @Override
   public Uri getUri() {
     return upstream.getUri();
   }
 
+  @Override
+  public Map<String, List<String>> getResponseHeaders() {
+    return upstream.getResponseHeaders();
+  }
+
+  @Override
+  public void close() throws IOException {
+    cipher = null;
+    upstream.close();
+  }
 }

library/hls/src/main/java/com/google/android/exoplayer2/source/hls/Aes128DataSource.java

@@ -27,6 +27,8 @@ import java.security.InvalidKeyException;
 import java.security.Key;
 import java.security.NoSuchAlgorithmException;
 import java.security.spec.AlgorithmParameterSpec;
+import java.util.List;
+import java.util.Map;
 import javax.crypto.Cipher;
 import javax.crypto.CipherInputStream;
 import javax.crypto.NoSuchPaddingException;
@@ -85,14 +87,6 @@ import javax.crypto.spec.SecretKeySpec;
     return C.LENGTH_UNSET;
   }
 
-  @Override
-  public void close() throws IOException {
-    if (cipherInputStream != null) {
-      cipherInputStream = null;
-      upstream.close();
-    }
-  }
-
   @Override
   public int read(byte[] buffer, int offset, int readLength) throws IOException {
     Assertions.checkState(cipherInputStream != null);
@@ -108,4 +102,16 @@ import javax.crypto.spec.SecretKeySpec;
     return upstream.getUri();
   }
 
+  @Override
+  public Map<String, List<String>> getResponseHeaders() {
+    return upstream.getResponseHeaders();
+  }
+
+  @Override
+  public void close() throws IOException {
+    if (cipherInputStream != null) {
+      cipherInputStream = null;
+      upstream.close();
+    }
+  }
 }