[Cronet] Respect user agent string from config

components/cronet/android/java/src/org/chromium/net/HttpUrlConnectionUrlRequestFactory.java

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.net;
 
 import android.content.Context;
 
 import java.io.IOException;
 import java.io.PrintWriter;
 import java.nio.channels.WritableByteChannel;
 import java.util.Map;
 
 /**
  * Network request using {@link java.net.HttpURLConnection}.
  */
 class HttpUrlConnectionUrlRequestFactory extends HttpUrlRequestFactory {
 
     private final Context mContext;
+    private final String mDefaultUserAgent;
 
     public HttpUrlConnectionUrlRequestFactory(
             Context context, UrlRequestContextConfig config) {
         mContext = context;
+        String userAgent = config.userAgent();
+        if (userAgent.isEmpty()) {
+            userAgent = UserAgent.from(mContext);
+        }
+        mDefaultUserAgent = userAgent;
     }
 
     @Override
     public boolean isEnabled() {
         return true;
     }
 
     @Override
     public String getName() {
         return "HttpUrlConnection/" + Version.getVersion();
     }
 
     @Override
     public HttpUrlRequest createRequest(String url, int requestPriority,
             Map<String, String> headers, HttpUrlRequestListener listener) {
-        return new HttpUrlConnectionUrlRequest(mContext, url, requestPriority,
-                headers, listener);
+        return new HttpUrlConnectionUrlRequest(mContext, mDefaultUserAgent, url,
+                requestPriority, headers, listener);
     }
 
     @Override
     public HttpUrlRequest createRequest(String url, int requestPriority,
             Map<String, String> headers, WritableByteChannel channel,
             HttpUrlRequestListener listener) {
-        return new HttpUrlConnectionUrlRequest(mContext, url, requestPriority,
-                headers, channel, listener);
+        return new HttpUrlConnectionUrlRequest(mContext, mDefaultUserAgent, url,
+                requestPriority, headers, channel, listener);
     }
 
     @Override
     public void startNetLogToFile(String fileName) {
         try {
             PrintWriter out = new PrintWriter(fileName);
             out.println("NetLog is not supported by " + getName());
             out.close();
         } catch (IOException e) {
             // Ignore any exceptions.
         }
     }
 
     @Override
     public void stopNetLog() {
     }
 }