Update ResponseInfo to UrlResponseInfo with API review comments.

components/cronet/android/java/src/org/chromium/net/urlconnection/CronetHttpURLConnection.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.urlconnection;
 
 import android.util.Pair;
 
 import org.chromium.base.Log;
 import org.chromium.net.ExtendedResponseInfo;
@@ skipping 126 matching lines @@
         List<String> values = map.get(fieldName);
         return values.get(values.size() - 1);
     }
 
     /**
      * Returns the name of the header field at the given position {@code pos}, or {@code null}
      * if there are fewer than {@code pos} fields.
      */
     @Override
     public final String getHeaderFieldKey(int pos) {
-        Pair<String, String> header = getHeaderFieldPair(pos);
+        Map.Entry<String, String> header = getHeaderFieldEntry(pos);
         if (header == null) {
             return null;
         }
-        return header.first;
+        return header.getKey();
     }
 
     /**
      * Returns the header value at the field position {@code pos} or {@code null} if the header
      * has fewer than {@code pos} fields.
      */
     @Override
     public final String getHeaderField(int pos) {
-        Pair<String, String> header = getHeaderFieldPair(pos);
+        Map.Entry<String, String> header = getHeaderFieldEntry(pos);
         if (header == null) {
             return null;
         }
-        return header.second;
+        return header.getValue();
     }
 
     /**
      * Returns an InputStream for reading data from the resource pointed by this
      * {@link java.net.URLConnection}.
      * @throws FileNotFoundException if http response code is equal or greater
      *             than {@link HTTP_BAD_REQUEST}.
      * @throws IOException If the request gets a network error or HTTP error
      *             status code, or if the caller tried to read the response body
      *             of a redirect when redirects are disabled.
@@ skipping 339 matching lines @@
             throw mException;
         } else if (mResponseInfo == null) {
             throw new NullPointerException(
                     "Response info is null when there is no exception.");
         }
     }
 
     /**
      * Helper method to return the response header field at position pos.
      */
-    private Pair<String, String> getHeaderFieldPair(int pos) {
+    private Map.Entry<String, String> getHeaderFieldEntry(int pos) {
         try {
             getResponse();
         } catch (IOException e) {
             return null;
         }
-        List<Pair<String, String>> headers =
-                mResponseInfo.getAllHeadersAsList();
+        List<Map.Entry<String, String>> headers = mResponseInfo.getAllHeadersAsList();
         if (pos >= headers.size()) {
             return null;
         }
         return headers.get(pos);
     }
 
     /**
      * Returns whether the client has used {@link #setChunkedStreamingMode} to
      * set chunked encoding for upload.
      */
     private boolean isChunkedUpload() {
         return chunkLength > 0;
     }
 }