Simplify using DataSource factories without a TransferListener.

Setting the transfer listener on the data source factories is only needed for debug
purposes, logging and for custom bandwidth metering which doesn't use the
player-provided bandwidth meter. As such, it is not compulsary and it should be easy
to set up the data source factory without a transfer listener.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=204926083

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

@@ -15,6 +15,7 @@
  */
 package com.google.android.exoplayer2.ext.cronet;
 
+import android.support.annotation.Nullable;
 import com.google.android.exoplayer2.upstream.DataSource;
 import com.google.android.exoplayer2.upstream.DefaultHttpDataSourceFactory;
 import com.google.android.exoplayer2.upstream.HttpDataSource;
@@ -46,7 +47,7 @@ public final class CronetDataSourceFactory extends BaseFactory {
   private final CronetEngineWrapper cronetEngineWrapper;
   private final Executor executor;
   private final Predicate<String> contentTypePredicate;
-  private final TransferListener<? super DataSource> transferListener;
+  private final @Nullable TransferListener<? super DataSource> transferListener;
   private final int connectTimeoutMs;
   private final int readTimeoutMs;
   private final boolean resetTimeoutOnRedirects;
@@ -54,26 +55,176 @@ public final class CronetDataSourceFactory extends BaseFactory {
 
   /**
    * Constructs a CronetDataSourceFactory.
-   * <p>
+   *
-   * If the {@link CronetEngineWrapper} fails to provide a {@link CronetEngine}, the provided
+   * <p>If the {@link CronetEngineWrapper} fails to provide a {@link CronetEngine}, the provided
    * fallback {@link HttpDataSource.Factory} will be used instead.
    *
-   * Sets {@link CronetDataSource#DEFAULT_CONNECT_TIMEOUT_MILLIS} as the connection timeout, {@link
+   * <p>Sets {@link CronetDataSource#DEFAULT_CONNECT_TIMEOUT_MILLIS} as the connection timeout,
-   * CronetDataSource#DEFAULT_READ_TIMEOUT_MILLIS} as the read timeout and disables
+   * {@link CronetDataSource#DEFAULT_READ_TIMEOUT_MILLIS} as the read timeout and disables
    * cross-protocol redirects.
    *
    * @param cronetEngineWrapper A {@link CronetEngineWrapper}.
    * @param executor The {@link java.util.concurrent.Executor} that will perform the requests.
    * @param contentTypePredicate An optional {@link Predicate}. If a content type is rejected by the
-   *     predicate then an {@link InvalidContentTypeException} is thrown from
+   *     predicate then an {@link InvalidContentTypeException} is thrown from {@link
-   *     {@link CronetDataSource#open}.
+   *     CronetDataSource#open}.
-   * @param transferListener An optional listener.
+   * @param fallbackFactory A {@link HttpDataSource.Factory} which is used as a fallback in case no
-   * @param fallbackFactory A {@link HttpDataSource.Factory} which is used as a fallback in case
+   *     suitable CronetEngine can be build.
-   *     no suitable CronetEngine can be build.
    */
-  public CronetDataSourceFactory(CronetEngineWrapper cronetEngineWrapper,
+  public CronetDataSourceFactory(
-      Executor executor, Predicate<String> contentTypePredicate,
+      CronetEngineWrapper cronetEngineWrapper,
-      TransferListener<? super DataSource> transferListener,
+      Executor executor,
+      Predicate<String> contentTypePredicate,
+      HttpDataSource.Factory fallbackFactory) {
+    this(
+        cronetEngineWrapper,
+        executor,
+        contentTypePredicate,
+        /* transferListener= */ null,
+        DEFAULT_CONNECT_TIMEOUT_MILLIS,
+        DEFAULT_READ_TIMEOUT_MILLIS,
+        false,
+        fallbackFactory);
+  }
+
+  /**
+   * Constructs a CronetDataSourceFactory.
+   *
+   * <p>If the {@link CronetEngineWrapper} fails to provide a {@link CronetEngine}, a {@link
+   * DefaultHttpDataSourceFactory} will be used instead.
+   *
+   * <p>Sets {@link CronetDataSource#DEFAULT_CONNECT_TIMEOUT_MILLIS} as the connection timeout,
+   * {@link CronetDataSource#DEFAULT_READ_TIMEOUT_MILLIS} as the read timeout and disables
+   * cross-protocol redirects.
+   *
+   * @param cronetEngineWrapper A {@link CronetEngineWrapper}.
+   * @param executor The {@link java.util.concurrent.Executor} that will perform the requests.
+   * @param contentTypePredicate An optional {@link Predicate}. If a content type is rejected by the
+   *     predicate then an {@link InvalidContentTypeException} is thrown from {@link
+   *     CronetDataSource#open}.
+   * @param userAgent A user agent used to create a fallback HttpDataSource if needed.
+   */
+  public CronetDataSourceFactory(
+      CronetEngineWrapper cronetEngineWrapper,
+      Executor executor,
+      Predicate<String> contentTypePredicate,
+      String userAgent) {
+    this(
+        cronetEngineWrapper,
+        executor,
+        contentTypePredicate,
+        /* transferListener= */ null,
+        DEFAULT_CONNECT_TIMEOUT_MILLIS,
+        DEFAULT_READ_TIMEOUT_MILLIS,
+        false,
+        new DefaultHttpDataSourceFactory(
+            userAgent,
+            /* listener= */ null,
+            DEFAULT_CONNECT_TIMEOUT_MILLIS,
+            DEFAULT_READ_TIMEOUT_MILLIS,
+            false));
+  }
+
+  /**
+   * Constructs a CronetDataSourceFactory.
+   *
+   * <p>If the {@link CronetEngineWrapper} fails to provide a {@link CronetEngine}, a {@link
+   * DefaultHttpDataSourceFactory} will be used instead.
+   *
+   * @param cronetEngineWrapper A {@link CronetEngineWrapper}.
+   * @param executor The {@link java.util.concurrent.Executor} that will perform the requests.
+   * @param contentTypePredicate An optional {@link Predicate}. If a content type is rejected by the
+   *     predicate then an {@link InvalidContentTypeException} is thrown from {@link
+   *     CronetDataSource#open}.
+   * @param connectTimeoutMs The connection timeout, in milliseconds.
+   * @param readTimeoutMs The read timeout, in milliseconds.
+   * @param resetTimeoutOnRedirects Whether the connect timeout is reset when a redirect occurs.
+   * @param userAgent A user agent used to create a fallback HttpDataSource if needed.
+   */
+  public CronetDataSourceFactory(
+      CronetEngineWrapper cronetEngineWrapper,
+      Executor executor,
+      Predicate<String> contentTypePredicate,
+      int connectTimeoutMs,
+      int readTimeoutMs,
+      boolean resetTimeoutOnRedirects,
+      String userAgent) {
+    this(
+        cronetEngineWrapper,
+        executor,
+        contentTypePredicate,
+        /* transferListener= */ null,
+        DEFAULT_CONNECT_TIMEOUT_MILLIS,
+        DEFAULT_READ_TIMEOUT_MILLIS,
+        resetTimeoutOnRedirects,
+        new DefaultHttpDataSourceFactory(
+            userAgent,
+            /* listener= */ null,
+            connectTimeoutMs,
+            readTimeoutMs,
+            resetTimeoutOnRedirects));
+  }
+
+  /**
+   * Constructs a CronetDataSourceFactory.
+   *
+   * <p>If the {@link CronetEngineWrapper} fails to provide a {@link CronetEngine}, the provided
+   * fallback {@link HttpDataSource.Factory} will be used instead.
+   *
+   * @param cronetEngineWrapper A {@link CronetEngineWrapper}.
+   * @param executor The {@link java.util.concurrent.Executor} that will perform the requests.
+   * @param contentTypePredicate An optional {@link Predicate}. If a content type is rejected by the
+   *     predicate then an {@link InvalidContentTypeException} is thrown from {@link
+   *     CronetDataSource#open}.
+   * @param connectTimeoutMs The connection timeout, in milliseconds.
+   * @param readTimeoutMs The read timeout, in milliseconds.
+   * @param resetTimeoutOnRedirects Whether the connect timeout is reset when a redirect occurs.
+   * @param fallbackFactory A {@link HttpDataSource.Factory} which is used as a fallback in case no
+   *     suitable CronetEngine can be build.
+   */
+  public CronetDataSourceFactory(
+      CronetEngineWrapper cronetEngineWrapper,
+      Executor executor,
+      Predicate<String> contentTypePredicate,
+      int connectTimeoutMs,
+      int readTimeoutMs,
+      boolean resetTimeoutOnRedirects,
+      HttpDataSource.Factory fallbackFactory) {
+    this(
+        cronetEngineWrapper,
+        executor,
+        contentTypePredicate,
+        /* transferListener= */ null,
+        connectTimeoutMs,
+        readTimeoutMs,
+        resetTimeoutOnRedirects,
+        fallbackFactory);
+  }
+
+  /**
+   * Constructs a CronetDataSourceFactory.
+   *
+   * <p>If the {@link CronetEngineWrapper} fails to provide a {@link CronetEngine}, the provided
+   * fallback {@link HttpDataSource.Factory} will be used instead.
+   *
+   * <p>Sets {@link CronetDataSource#DEFAULT_CONNECT_TIMEOUT_MILLIS} as the connection timeout,
+   * {@link CronetDataSource#DEFAULT_READ_TIMEOUT_MILLIS} as the read timeout and disables
+   * cross-protocol redirects.
+   *
+   * @param cronetEngineWrapper A {@link CronetEngineWrapper}.
+   * @param executor The {@link java.util.concurrent.Executor} that will perform the requests.
+   * @param contentTypePredicate An optional {@link Predicate}. If a content type is rejected by the
+   *     predicate then an {@link InvalidContentTypeException} is thrown from {@link
+   *     CronetDataSource#open}.
+   * @param transferListener An optional listener.
+   * @param fallbackFactory A {@link HttpDataSource.Factory} which is used as a fallback in case no
+   *     suitable CronetEngine can be build.
+   */
+  public CronetDataSourceFactory(
+      CronetEngineWrapper cronetEngineWrapper,
+      Executor executor,
+      Predicate<String> contentTypePredicate,
+      @Nullable TransferListener<? super DataSource> transferListener,
       HttpDataSource.Factory fallbackFactory) {
     this(cronetEngineWrapper, executor, contentTypePredicate, transferListener,
         DEFAULT_CONNECT_TIMEOUT_MILLIS, DEFAULT_READ_TIMEOUT_MILLIS, false, fallbackFactory);
@@ -81,25 +232,28 @@ public final class CronetDataSourceFactory extends BaseFactory {
 
   /**
    * Constructs a CronetDataSourceFactory.
-   * <p>
-   * If the {@link CronetEngineWrapper} fails to provide a {@link CronetEngine}, a
-   * {@link DefaultHttpDataSourceFactory} will be used instead.
    *
-   * Sets {@link CronetDataSource#DEFAULT_CONNECT_TIMEOUT_MILLIS} as the connection timeout, {@link
+   * <p>If the {@link CronetEngineWrapper} fails to provide a {@link CronetEngine}, a {@link
-   * CronetDataSource#DEFAULT_READ_TIMEOUT_MILLIS} as the read timeout and disables
+   * DefaultHttpDataSourceFactory} will be used instead.
+   *
+   * <p>Sets {@link CronetDataSource#DEFAULT_CONNECT_TIMEOUT_MILLIS} as the connection timeout,
+   * {@link CronetDataSource#DEFAULT_READ_TIMEOUT_MILLIS} as the read timeout and disables
    * cross-protocol redirects.
    *
    * @param cronetEngineWrapper A {@link CronetEngineWrapper}.
    * @param executor The {@link java.util.concurrent.Executor} that will perform the requests.
    * @param contentTypePredicate An optional {@link Predicate}. If a content type is rejected by the
-   *     predicate then an {@link InvalidContentTypeException} is thrown from
+   *     predicate then an {@link InvalidContentTypeException} is thrown from {@link
-   *     {@link CronetDataSource#open}.
+   *     CronetDataSource#open}.
    * @param transferListener An optional listener.
    * @param userAgent A user agent used to create a fallback HttpDataSource if needed.
    */
-  public CronetDataSourceFactory(CronetEngineWrapper cronetEngineWrapper,
+  public CronetDataSourceFactory(
-      Executor executor, Predicate<String> contentTypePredicate,
+      CronetEngineWrapper cronetEngineWrapper,
-      TransferListener<? super DataSource> transferListener, String userAgent) {
+      Executor executor,
+      Predicate<String> contentTypePredicate,
+      @Nullable TransferListener<? super DataSource> transferListener,
+      String userAgent) {
     this(cronetEngineWrapper, executor, contentTypePredicate, transferListener,
         DEFAULT_CONNECT_TIMEOUT_MILLIS, DEFAULT_READ_TIMEOUT_MILLIS, false,
         new DefaultHttpDataSourceFactory(userAgent, transferListener,
@@ -108,25 +262,30 @@ public final class CronetDataSourceFactory extends BaseFactory {
 
   /**
    * Constructs a CronetDataSourceFactory.
-   * <p>
+   *
-   * If the {@link CronetEngineWrapper} fails to provide a {@link CronetEngine}, a
+   * <p>If the {@link CronetEngineWrapper} fails to provide a {@link CronetEngine}, a {@link
-   * {@link DefaultHttpDataSourceFactory} will be used instead.
+   * DefaultHttpDataSourceFactory} will be used instead.
    *
    * @param cronetEngineWrapper A {@link CronetEngineWrapper}.
    * @param executor The {@link java.util.concurrent.Executor} that will perform the requests.
    * @param contentTypePredicate An optional {@link Predicate}. If a content type is rejected by the
-   *     predicate then an {@link InvalidContentTypeException} is thrown from
+   *     predicate then an {@link InvalidContentTypeException} is thrown from {@link
-   *     {@link CronetDataSource#open}.
+   *     CronetDataSource#open}.
    * @param transferListener An optional listener.
    * @param connectTimeoutMs The connection timeout, in milliseconds.
    * @param readTimeoutMs The read timeout, in milliseconds.
    * @param resetTimeoutOnRedirects Whether the connect timeout is reset when a redirect occurs.
    * @param userAgent A user agent used to create a fallback HttpDataSource if needed.
    */
-  public CronetDataSourceFactory(CronetEngineWrapper cronetEngineWrapper,
+  public CronetDataSourceFactory(
-      Executor executor, Predicate<String> contentTypePredicate,
+      CronetEngineWrapper cronetEngineWrapper,
-      TransferListener<? super DataSource> transferListener, int connectTimeoutMs,
+      Executor executor,
-      int readTimeoutMs, boolean resetTimeoutOnRedirects, String userAgent) {
+      Predicate<String> contentTypePredicate,
+      @Nullable TransferListener<? super DataSource> transferListener,
+      int connectTimeoutMs,
+      int readTimeoutMs,
+      boolean resetTimeoutOnRedirects,
+      String userAgent) {
     this(cronetEngineWrapper, executor, contentTypePredicate, transferListener,
         DEFAULT_CONNECT_TIMEOUT_MILLIS, DEFAULT_READ_TIMEOUT_MILLIS, resetTimeoutOnRedirects,
         new DefaultHttpDataSourceFactory(userAgent, transferListener, connectTimeoutMs,
@@ -135,26 +294,30 @@ public final class CronetDataSourceFactory extends BaseFactory {
 
   /**
    * Constructs a CronetDataSourceFactory.
-   * <p>
+   *
-   * If the {@link CronetEngineWrapper} fails to provide a {@link CronetEngine}, the provided
+   * <p>If the {@link CronetEngineWrapper} fails to provide a {@link CronetEngine}, the provided
    * fallback {@link HttpDataSource.Factory} will be used instead.
    *
    * @param cronetEngineWrapper A {@link CronetEngineWrapper}.
    * @param executor The {@link java.util.concurrent.Executor} that will perform the requests.
    * @param contentTypePredicate An optional {@link Predicate}. If a content type is rejected by the
-   *     predicate then an {@link InvalidContentTypeException} is thrown from
+   *     predicate then an {@link InvalidContentTypeException} is thrown from {@link
-   *     {@link CronetDataSource#open}.
+   *     CronetDataSource#open}.
    * @param transferListener An optional listener.
    * @param connectTimeoutMs The connection timeout, in milliseconds.
    * @param readTimeoutMs The read timeout, in milliseconds.
    * @param resetTimeoutOnRedirects Whether the connect timeout is reset when a redirect occurs.
-   * @param fallbackFactory A {@link HttpDataSource.Factory} which is used as a fallback in case
+   * @param fallbackFactory A {@link HttpDataSource.Factory} which is used as a fallback in case no
-   *     no suitable CronetEngine can be build.
+   *     suitable CronetEngine can be build.
    */
-  public CronetDataSourceFactory(CronetEngineWrapper cronetEngineWrapper,
+  public CronetDataSourceFactory(
-      Executor executor, Predicate<String> contentTypePredicate,
+      CronetEngineWrapper cronetEngineWrapper,
-      TransferListener<? super DataSource> transferListener, int connectTimeoutMs,
+      Executor executor,
-      int readTimeoutMs, boolean resetTimeoutOnRedirects,
+      Predicate<String> contentTypePredicate,
+      @Nullable TransferListener<? super DataSource> transferListener,
+      int connectTimeoutMs,
+      int readTimeoutMs,
+      boolean resetTimeoutOnRedirects,
       HttpDataSource.Factory fallbackFactory) {
     this.cronetEngineWrapper = cronetEngineWrapper;
     this.executor = executor;

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

@@ -35,6 +35,28 @@ public final class OkHttpDataSourceFactory extends BaseFactory {
   @Nullable private final TransferListener<? super DataSource> listener;
   @Nullable private final CacheControl cacheControl;
 
+  /**
+   * @param callFactory A {@link Call.Factory} (typically an {@link okhttp3.OkHttpClient}) for use
+   *     by the sources created by the factory.
+   * @param userAgent An optional User-Agent string.
+   */
+  public OkHttpDataSourceFactory(@NonNull Call.Factory callFactory, @Nullable String userAgent) {
+    this(callFactory, userAgent, /* listener= */ null, /* cacheControl= */ null);
+  }
+
+  /**
+   * @param callFactory A {@link Call.Factory} (typically an {@link okhttp3.OkHttpClient}) for use
+   *     by the sources created by the factory.
+   * @param userAgent An optional User-Agent string.
+   * @param cacheControl An optional {@link CacheControl} for setting the Cache-Control header.
+   */
+  public OkHttpDataSourceFactory(
+      @NonNull Call.Factory callFactory,
+      @Nullable String userAgent,
+      @Nullable CacheControl cacheControl) {
+    this(callFactory, userAgent, /* listener= */ null, cacheControl);
+  }
+
   /**
    * @param callFactory A {@link Call.Factory} (typically an {@link okhttp3.OkHttpClient}) for use
    *     by the sources created by the factory.
@@ -43,7 +65,7 @@ public final class OkHttpDataSourceFactory extends BaseFactory {
    */
   public OkHttpDataSourceFactory(@NonNull Call.Factory callFactory, @Nullable String userAgent,
       @Nullable TransferListener<? super DataSource> listener) {
-    this(callFactory, userAgent, listener, null);
+    this(callFactory, userAgent, listener, /* cacheControl= */ null);
   }
 
   /**
@@ -68,5 +90,4 @@ public final class OkHttpDataSourceFactory extends BaseFactory {
     return new OkHttpDataSource(callFactory, userAgent, null, listener, cacheControl,
         defaultRequestProperties);
   }
-
 }

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

@@ -16,6 +16,7 @@
 package com.google.android.exoplayer2.upstream;
 
 import android.content.Context;
+import android.support.annotation.Nullable;
 import com.google.android.exoplayer2.upstream.DataSource.Factory;
 
 /**
@@ -25,7 +26,7 @@ import com.google.android.exoplayer2.upstream.DataSource.Factory;
 public final class DefaultDataSourceFactory implements Factory {
 
   private final Context context;
-  private final TransferListener<? super DataSource> listener;
+  private final @Nullable TransferListener<? super DataSource> listener;
   private final DataSource.Factory baseDataSourceFactory;
 
   /**
@@ -33,7 +34,7 @@ public final class DefaultDataSourceFactory implements Factory {
    * @param userAgent The User-Agent string that should be used.
    */
   public DefaultDataSourceFactory(Context context, String userAgent) {
-    this(context, userAgent, null);
+    this(context, userAgent, /* listener= */ null);
   }
 
   /**
@@ -41,11 +42,21 @@ public final class DefaultDataSourceFactory implements Factory {
    * @param userAgent The User-Agent string that should be used.
    * @param listener An optional listener.
    */
-  public DefaultDataSourceFactory(Context context, String userAgent,
+  public DefaultDataSourceFactory(
-      TransferListener<? super DataSource> listener) {
+      Context context, String userAgent, @Nullable TransferListener<? super DataSource> listener) {
     this(context, listener, new DefaultHttpDataSourceFactory(userAgent, listener));
   }
 
+  /**
+   * @param context A context.
+   * @param baseDataSourceFactory A {@link Factory} to be used to create a base {@link DataSource}
+   *     for {@link DefaultDataSource}.
+   * @see DefaultDataSource#DefaultDataSource(Context, TransferListener, DataSource)
+   */
+  public DefaultDataSourceFactory(Context context, DataSource.Factory baseDataSourceFactory) {
+    this(context, /* listener= */ null, baseDataSourceFactory);
+  }
+
   /**
    * @param context A context.
    * @param listener An optional listener.
@@ -53,7 +64,9 @@ public final class DefaultDataSourceFactory implements Factory {
    *     for {@link DefaultDataSource}.
    * @see DefaultDataSource#DefaultDataSource(Context, TransferListener, DataSource)
    */
-  public DefaultDataSourceFactory(Context context, TransferListener<? super DataSource> listener,
+  public DefaultDataSourceFactory(
+      Context context,
+      @Nullable TransferListener<? super DataSource> listener,
       DataSource.Factory baseDataSourceFactory) {
     this.context = context.getApplicationContext();
     this.listener = listener;
@@ -64,5 +77,4 @@ public final class DefaultDataSourceFactory implements Factory {
   public DefaultDataSource createDataSource() {
     return new DefaultDataSource(context, listener, baseDataSourceFactory.createDataSource());
   }
-
 }

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

@@ -15,6 +15,7 @@
  */
 package com.google.android.exoplayer2.upstream;
 
+import android.support.annotation.Nullable;
 import com.google.android.exoplayer2.upstream.HttpDataSource.BaseFactory;
 import com.google.android.exoplayer2.upstream.HttpDataSource.Factory;
 
@@ -22,7 +23,7 @@ import com.google.android.exoplayer2.upstream.HttpDataSource.Factory;
 public final class DefaultHttpDataSourceFactory extends BaseFactory {
 
   private final String userAgent;
-  private final TransferListener<? super DataSource> listener;
+  private final @Nullable TransferListener<? super DataSource> listener;
   private final int connectTimeoutMillis;
   private final int readTimeoutMillis;
   private final boolean allowCrossProtocolRedirects;
@@ -50,11 +51,33 @@ public final class DefaultHttpDataSourceFactory extends BaseFactory {
    * @see #DefaultHttpDataSourceFactory(String, TransferListener, int, int, boolean)
    */
   public DefaultHttpDataSourceFactory(
-      String userAgent, TransferListener<? super DataSource> listener) {
+      String userAgent, @Nullable TransferListener<? super DataSource> listener) {
     this(userAgent, listener, DefaultHttpDataSource.DEFAULT_CONNECT_TIMEOUT_MILLIS,
         DefaultHttpDataSource.DEFAULT_READ_TIMEOUT_MILLIS, false);
   }
 
+  /**
+   * @param userAgent The User-Agent string that should be used.
+   * @param connectTimeoutMillis The connection timeout that should be used when requesting remote
+   *     data, in milliseconds. A timeout of zero is interpreted as an infinite timeout.
+   * @param readTimeoutMillis The read timeout that should be used when requesting remote data, in
+   *     milliseconds. A timeout of zero is interpreted as an infinite timeout.
+   * @param allowCrossProtocolRedirects Whether cross-protocol redirects (i.e. redirects from HTTP
+   *     to HTTPS and vice versa) are enabled.
+   */
+  public DefaultHttpDataSourceFactory(
+      String userAgent,
+      int connectTimeoutMillis,
+      int readTimeoutMillis,
+      boolean allowCrossProtocolRedirects) {
+    this(
+        userAgent,
+        /* listener= */ null,
+        connectTimeoutMillis,
+        readTimeoutMillis,
+        allowCrossProtocolRedirects);
+  }
+
   /**
    * @param userAgent The User-Agent string that should be used.
    * @param listener An optional listener.
@@ -65,9 +88,12 @@ public final class DefaultHttpDataSourceFactory extends BaseFactory {
    * @param allowCrossProtocolRedirects Whether cross-protocol redirects (i.e. redirects from HTTP
    *     to HTTPS and vice versa) are enabled.
    */
-  public DefaultHttpDataSourceFactory(String userAgent,
+  public DefaultHttpDataSourceFactory(
-      TransferListener<? super DataSource> listener, int connectTimeoutMillis,
+      String userAgent,
-      int readTimeoutMillis, boolean allowCrossProtocolRedirects) {
+      @Nullable TransferListener<? super DataSource> listener,
+      int connectTimeoutMillis,
+      int readTimeoutMillis,
+      boolean allowCrossProtocolRedirects) {
     this.userAgent = userAgent;
     this.listener = listener;
     this.connectTimeoutMillis = connectTimeoutMillis;
@@ -81,5 +107,4 @@ public final class DefaultHttpDataSourceFactory extends BaseFactory {
     return new DefaultHttpDataSource(userAgent, null, listener, connectTimeoutMillis,
         readTimeoutMillis, allowCrossProtocolRedirects, defaultRequestProperties);
   }
-
 }