Create org.chromium.content_public.common and move two classes there.

content/public/android/java/src/org/chromium/content_public/Referrer.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.content_public;
-
-/**
- * Container that holds together a referrer URL along with the referrer policy set on the
- * originating frame. This corresponds to native content/public/common/referrer.h.
- */
-public class Referrer {
-    private final String mUrl;
-    private final int mPolicy;
-
-    public Referrer(String url, int policy) {
-        mUrl = url;
-        mPolicy = policy;
-    }
-
-    public String getUrl() {
-        return mUrl;
-    }
-
-    public int getPolicy() {
-        return mPolicy;
-    }
-}