Implement Android key/value backup

chrome/browser/android/chrome_backup_watcher.cc

Index: chrome/browser/android/chrome_backup_watcher.cc
diff --git a/chrome/browser/android/chrome_backup_watcher.cc b/chrome/browser/android/chrome_backup_watcher.cc
new file mode 100644
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+++ b/chrome/browser/android/chrome_backup_watcher.cc
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+// 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.
+
+#include "chrome/browser/android/chrome_backup_agent.h"
+#include "chrome/browser/android/chrome_backup_watcher.h"
+#include "chrome/browser/profiles/profile.h"
+#include "jni/ChromeBackupWatcher_jni.h"
+
+namespace chrome {
+namespace android {
+
+namespace {
+
+void BackupPrefsChanged(
+    const base::android::ScopedJavaGlobalRef<jobject>& java_watcher) {
+  Java_ChromeBackupWatcher_onBackupPrefsChanged(
+      base::android::AttachCurrentThread(), java_watcher);
+}
+}
+
+ChromeBackupWatcher::ChromeBackupWatcher(Profile* profile) {
+  JNIEnv* env = base::android::AttachCurrentThread();
+  // Create the Java class, and start watching the Android (Java) preferences
+  java_watcher_.Reset(Java_ChromeBackupWatcher_createChromeBackupWatcher(env));
+  // Now watch the Chrome C++ preferences
+  registrar_.Init(profile->GetPrefs());
+  base::RepeatingClosure callback =
+      base::BindRepeating(&BackupPrefsChanged, java_watcher_);
+  for (const std::string pref_name : GetBackupPrefNames()) {
+    registrar_.Add(pref_name, callback);
+  }
+}
+
+ChromeBackupWatcher::~ChromeBackupWatcher() {}
+
+}  //  namespace android
+}  //  namespace chrome