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 backup using Android Backup, so that we can

[Bernhard Bauer, 2016/11/14 10:05:39]

Nit: the verb is "back up", only the noun is "backup" :)

[aberent, 2016/11/14 17:23:40]

Done.

[Bernhard Bauer, 2016/11/14 18:02:03]

Thanks. The correct use of the three forms "back up", "Backup" and "backup" in a
single sentence now makes me happier than I care to admit ;-)

+// create a new backup whenever any of them change.
+class ChromeBackupWatcher {
+ public:
+  explicit ChromeBackupWatcher(Profile* profile);

[Bernhard Bauer, 2016/11/14 10:05:39]

Add an empty destructor?

[aberent, 2016/11/14 17:23:40]

Done.

+
+ private:
+  std::unique_ptr<PrefChangeRegistrar> registrar_;

[Bernhard Bauer, 2016/11/14 10:05:39]

Make this a direct member?

[aberent, 2016/11/14 17:23:40]

Done.

+  base::android::ScopedJavaGlobalRef<jobject> java_watcher_;
+  DISALLOW_COPY_AND_ASSIGN(ChromeBackupWatcher);
+};
+
+}  //  namespace android
+}  //  namespace chrome
+#endif  // CHROME_BROWSER_ANDROID_CHROME_BACKUP_WATCHER_H_