Revert of Implement Android key/value backup

chrome/browser/android/chrome_backup_watcher.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_WATCHER_H_
-#define CHROME_BROWSER_ANDROID_CHROME_BACKUP_WATCHER_H_
-
-#include <jni.h>
-
-#include <memory>
-
-#include "base/android/scoped_java_ref.h"
-#include "base/macros.h"
-#include "components/prefs/pref_change_registrar.h"
-
-class Profile;
-
-namespace chrome {
-namespace android {
-
-// Watch the preferences that we back up using Android Backup, so that we can
-// create a new backup whenever any of them change.
-class ChromeBackupWatcher {
- public:
-  explicit ChromeBackupWatcher(Profile* profile);
-  virtual ~ChromeBackupWatcher();
-
- private:
-  PrefChangeRegistrar registrar_;
-  base::android::ScopedJavaGlobalRef<jobject> java_watcher_;
-  DISALLOW_COPY_AND_ASSIGN(ChromeBackupWatcher);
-};
-
-}  //  namespace android
-}  //  namespace chrome
-#endif  // CHROME_BROWSER_ANDROID_CHROME_BACKUP_WATCHER_H_