Update ResponseInfo to UrlResponseInfo with API review comments.

components/cronet/android/java/src/org/chromium/net/urlconnection/CronetHttpURLConnection.java

Index: components/cronet/android/java/src/org/chromium/net/urlconnection/CronetHttpURLConnection.java
diff --git a/components/cronet/android/java/src/org/chromium/net/urlconnection/CronetHttpURLConnection.java b/components/cronet/android/java/src/org/chromium/net/urlconnection/CronetHttpURLConnection.java
index 89bf7b69035c66835b24b6b39b535c90b16931e5..93df2a54dadf64a5c2dc0063280b5fd3c6b8d4c3 100644
--- a/components/cronet/android/java/src/org/chromium/net/urlconnection/CronetHttpURLConnection.java
+++ b/components/cronet/android/java/src/org/chromium/net/urlconnection/CronetHttpURLConnection.java
@@ -144,11 +144,11 @@ class CronetHttpURLConnection extends HttpURLConnection {
      */
     @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();
     }
 
     /**
@@ -157,11 +157,11 @@ class CronetHttpURLConnection extends HttpURLConnection {
      */
     @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();
     }
 
     /**
@@ -521,14 +521,13 @@ class CronetHttpURLConnection extends HttpURLConnection {
     /**
      * 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;
         }