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 48b4dc79010dd732c5a26e2b0890e7955cf5a6d5..dc7c8f98829282dfb1c4f07ca03c4e81774d87fe 100644
--- a/chrome/browser/BUILD.gn
+++ b/chrome/browser/BUILD.gn
@@ -2932,6 +2932,9 @@ 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",
@@ -3815,6 +3818,8 @@ 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",