Implement Android key/value backup

chrome/browser/android/chrome_backup_agent.h

+// Copyright 2016 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.
+
+#ifndef CHROME_BROWSER_ANDROID_CHROME_BACKUP_AGENT_H_
+#define CHROME_BROWSER_ANDROID_CHROME_BACKUP_AGENT_H_
+
+#include <jni.h>
+
+#include <string>
+#include <vector>
+
+namespace chrome {
+namespace android {
+
+std::vector<std::string> GetBackupPrefNames();
+
+bool RegisterBackupAgent(JNIEnv* env);
+
+}  //  namespace android
+}  //  namespace chrome
+
+#endif  // CHROME_BROWSER_ANDROID_CHROME_BACKUP_AGENT_H_