Implement Android key/value backup

chrome/browser/BUILD.gn

Index: chrome/browser/BUILD.gn
diff --git a/chrome/browser/BUILD.gn b/chrome/browser/BUILD.gn
index 87409e5e5df807664b2d8bef8407acab025e40f7..af662757b3e2c205a5b8881cda5168806b5e8520 100644
--- a/chrome/browser/BUILD.gn
+++ b/chrome/browser/BUILD.gn
@@ -2898,6 +2898,9 @@ split_static_library("browser") {
       "android/browsing_data/url_filter_bridge.h",
       "android/chrome_application.cc",
       "android/chrome_application.h",
+      "android/chrome_backup_agent.cc",
+      "android/chrome_backup_agent.h",
+      "android/chrome_backup_watcher.cc",
       "android/chrome_feature_list.cc",
       "android/chrome_feature_list.h",
       "android/chrome_jni_registrar.cc",
@@ -3734,6 +3737,8 @@ if (android_java_ui) {
       "../android/java/src/org/chromium/chrome/browser/BackgroundSyncLauncher.java",
       "../android/java/src/org/chromium/chrome/browser/BluetoothChooserDialog.java",
       "../android/java/src/org/chromium/chrome/browser/ChromeApplication.java",
+      "../android/java/src/org/chromium/chrome/browser/ChromeBackupAgent.java",
+      "../android/java/src/org/chromium/chrome/browser/ChromeBackupWatcher.java",
       "../android/java/src/org/chromium/chrome/browser/ChromeFeatureList.java",
       "../android/java/src/org/chromium/chrome/browser/ChromeHttpAuthHandler.java",
       "../android/java/src/org/chromium/chrome/browser/DevToolsServer.java",