Support setting default headers on HttpDataSource.Factory's

Issue: #2166

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=143703258

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

@@ -16,6 +16,7 @@
 package com.google.android.exoplayer2.ext.cronet;
 
 import com.google.android.exoplayer2.upstream.DataSource;
+import com.google.android.exoplayer2.upstream.HttpDataSource.BaseFactory;
 import com.google.android.exoplayer2.upstream.HttpDataSource.Factory;
 import com.google.android.exoplayer2.upstream.TransferListener;
 import com.google.android.exoplayer2.util.Predicate;
@@ -25,7 +26,7 @@ import org.chromium.net.CronetEngine;
 /**
  * A {@link Factory} that produces {@link CronetDataSource}.
  */
-public final class CronetDataSourceFactory implements Factory {
+public final class CronetDataSourceFactory extends BaseFactory {
 
   /**
    * The default connection timeout, in milliseconds.
@@ -67,7 +68,7 @@ public final class CronetDataSourceFactory implements Factory {
   }
 
   @Override
-  public CronetDataSource createDataSource() {
+  protected CronetDataSource createDataSourceInternal() {
     return new CronetDataSource(cronetEngine, executor, contentTypePredicate, transferListener,
         connectTimeoutMs, readTimeoutMs, resetTimeoutOnRedirects);
   }

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

@@ -16,6 +16,7 @@
 package com.google.android.exoplayer2.ext.okhttp;
 
 import com.google.android.exoplayer2.upstream.DataSource;
+import com.google.android.exoplayer2.upstream.HttpDataSource.BaseFactory;
 import com.google.android.exoplayer2.upstream.HttpDataSource.Factory;
 import com.google.android.exoplayer2.upstream.TransferListener;
 import okhttp3.CacheControl;
@@ -24,7 +25,7 @@ import okhttp3.Call;
 /**
  * A {@link Factory} that produces {@link OkHttpDataSource}.
  */
-public final class OkHttpDataSourceFactory implements Factory {
+public final class OkHttpDataSourceFactory extends BaseFactory {
 
   private final Call.Factory callFactory;
   private final String userAgent;
@@ -58,7 +59,7 @@ public final class OkHttpDataSourceFactory implements Factory {
   }
 
   @Override
-  public OkHttpDataSource createDataSource() {
+  protected OkHttpDataSource createDataSourceInternal() {
     return new OkHttpDataSource(callFactory, userAgent, null, listener, cacheControl);
   }
 

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

@@ -15,10 +15,11 @@
  */
 package com.google.android.exoplayer2.upstream;
 
+import com.google.android.exoplayer2.upstream.HttpDataSource.BaseFactory;
 import com.google.android.exoplayer2.upstream.HttpDataSource.Factory;
 
 /** A {@link Factory} that produces {@link DefaultHttpDataSource} instances. */
-public final class DefaultHttpDataSourceFactory implements Factory {
+public final class DefaultHttpDataSourceFactory extends BaseFactory {
 
   private final String userAgent;
   private final TransferListener<? super DataSource> listener;
@@ -75,8 +76,9 @@ public final class DefaultHttpDataSourceFactory implements Factory {
   }
 
   @Override
-  public DefaultHttpDataSource createDataSource() {
+  protected DefaultHttpDataSource createDataSourceInternal() {
     return new DefaultHttpDataSource(userAgent, null, listener, connectTimeoutMillis,
         readTimeoutMillis, allowCrossProtocolRedirects);
   }
+
 }

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

@@ -17,11 +17,13 @@ package com.google.android.exoplayer2.upstream;
 
 import android.support.annotation.IntDef;
 import android.text.TextUtils;
+import com.google.android.exoplayer2.util.Assertions;
 import com.google.android.exoplayer2.util.Predicate;
 import com.google.android.exoplayer2.util.Util;
 import java.io.IOException;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
+import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 
@@ -38,6 +40,86 @@ public interface HttpDataSource extends DataSource {
     @Override
     HttpDataSource createDataSource();
 
+    /**
+     * Sets a default request header field for {@link HttpDataSource} instances subsequently
+     * created by the factory. Previously created instances are not affected.
+     *
+     * @param name The name of the header field.
+     * @param value The value of the field.
+     */
+    void setDefaultRequestProperty(String name, String value);
+
+    /**
+     * Clears a default request header field for {@link HttpDataSource} instances subsequently
+     * created by the factory. Previously created instances are not affected.
+     *
+     * @param name The name of the header field.
+     */
+    void clearDefaultRequestProperty(String name);
+
+    /**
+     * Clears all default request header fields for all {@link HttpDataSource} instances
+     * subsequently created by the factory.  Previously created instances are not affected.
+     */
+    void clearAllDefaultRequestProperties();
+
+  }
+
+  /**
+   * Base implementation of {@link Factory} that sets default request properties.
+   */
+  abstract class BaseFactory implements Factory {
+
+    private final HashMap<String, String> requestProperties;
+
+    public BaseFactory() {
+      requestProperties = new HashMap<>();
+    }
+
+    @Override
+    public final HttpDataSource createDataSource() {
+      HttpDataSource dataSource = createDataSourceInternal();
+      synchronized (requestProperties) {
+        for (Map.Entry<String, String> property : requestProperties.entrySet()) {
+          dataSource.setRequestProperty(property.getKey(), property.getValue());
+        }
+      }
+      return dataSource;
+    }
+
+    @Override
+    public final void setDefaultRequestProperty(String name, String value) {
+      Assertions.checkNotNull(name);
+      Assertions.checkNotNull(value);
+      synchronized (requestProperties) {
+        requestProperties.put(name, value);
+      }
+    }
+
+    @Override
+    public final void clearDefaultRequestProperty(String name) {
+      Assertions.checkNotNull(name);
+      synchronized (requestProperties) {
+        requestProperties.remove(name);
+      }
+    }
+
+    @Override
+    public final void clearAllDefaultRequestProperties() {
+      synchronized (requestProperties) {
+        requestProperties.clear();
+      }
+    }
+
+    /**
+     * Called by {@link #createDataSource()} to create a {@link HttpDataSource} instance without
+     * default request properties set. Default request properties will be set by
+     * {@link #createDataSource()} before the instance is returned.
+     *
+     * @return A {@link HttpDataSource} instance without default request properties set.
+     */
+    protected abstract HttpDataSource createDataSourceInternal();
+
   }
 
   /**