Implement extension controlled indicators, starting with New Tab page

chrome/browser/ui/webui/settings/on_startup_handler.cc

Index: chrome/browser/ui/webui/settings/on_startup_handler.cc
diff --git a/chrome/browser/ui/webui/settings/on_startup_handler.cc b/chrome/browser/ui/webui/settings/on_startup_handler.cc
new file mode 100644
index 0000000000000000000000000000000000000000..000bc899242126e5d215288222449b76f2ce4ace
--- /dev/null
+++ b/chrome/browser/ui/webui/settings/on_startup_handler.cc
@@ -0,0 +1,53 @@
+// 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/ui/webui/settings/on_startup_handler.h"
+
+#include "base/bind.h"
+#include "base/bind_helpers.h"
+#include "base/logging.h"
+#include "chrome/browser/extensions/settings_api_helpers.h"
+#include "chrome/browser/profiles/profile.h"
+#include "content/public/browser/web_ui.h"
+#include "extensions/browser/extension_system.h"
+#include "extensions/browser/management_policy.h"
+#include "extensions/common/extension.h"
+
+namespace settings {
+
+OnStartupHandler::OnStartupHandler() {}
+OnStartupHandler::~OnStartupHandler() {}
+
+void OnStartupHandler::RegisterMessages() {
+  web_ui()->RegisterMessageCallback(
+      "getNtpExtension", base::Bind(&OnStartupHandler::HandleGetNtpExtension,
+                                    base::Unretained(this)));
+}
+
+void OnStartupHandler::HandleGetNtpExtension(const base::ListValue* args) {
+  const base::Value* callback_id;
+  CHECK(args->Get(0, &callback_id));
+
+  AllowJavascript();
+
+  Profile* profile = Profile::FromWebUI(web_ui());
+  const extensions::Extension* ntp_extension =
+      extensions::GetExtensionOverridingNewTabPage(profile);
+
+  if (!ntp_extension) {
+    ResolveJavascriptCallback(*callback_id, *base::Value::CreateNullValue());
+    return;
+  }
+
+  base::DictionaryValue dict;
+  dict.SetString("id", ntp_extension->id());
+  dict.SetString("name", ntp_extension->name());
+  dict.SetBoolean("canBeDisabled",
+                  !extensions::ExtensionSystem::Get(profile)
+                       ->management_policy()
+                       ->MustRemainEnabled(ntp_extension, nullptr));
+  ResolveJavascriptCallback(*callback_id, dict);
+}
+
+}  // namespace settings