Move Android user agent generation to native code

content/public/android/java/src/org/chromium/content/app/UserAgent.java

-// Copyright (c) 2012 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.app;
-
-import android.os.Build;
-
-import org.chromium.base.CalledByNative;
-
-/**
- * Provides necessary information for building the user agent string.
- */
-class UserAgent {
-    // TODO(yfriedman): Keep this reasonably up to date.
-    private static final String PREVIOUS_VERSION = "4.0.3";
-
-    @CalledByNative
-    static String getUserAgentOSInfo() {
-        String osInfo = "";
-        final String version = Build.VERSION.RELEASE;
-        if (version.length() > 0) {
-            if (Character.isDigit(version.charAt(0))) {
-                // Release is a version, eg "3.1"
-                osInfo += version;
-            } else {
-                // Release doesn't have a version number yet, eg "Honeycomb"
-                // In this case, use the previous release's version
-                osInfo += PREVIOUS_VERSION;
-            }
-        } else {
-            // default to "1.0"
-            osInfo += "1.0";
-        }
-        osInfo += ";";
-
-        if ("REL".equals(Build.VERSION.CODENAME)) {
-            final String model = Build.MODEL;
-            if (model.length() > 0) {
-                osInfo += " " + model;
-            }
-        }
-        final String id = Build.ID;
-        if (id.length() > 0) {
-            osInfo += " Build/" + id;
-        }
-
-        return osInfo;
-    }
-}