Implement extension controlled indicators, starting with New Tab page

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

+// 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() {}

[dpapad, 2016/11/17 01:16:46]

Same question here. Can we just use the existing
https://cs.chromium.org/chromium/src/chrome/browser/ui/webui/settings/setting...
(perhaps rename it too)?

[Dan Beam, 2016/11/17 02:51:47]

Acknowledged.

+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));

[dpapad, 2016/11/17 01:50:07]

Nit: Having the "->" on this line instead of previous seems a bit odd. Maybe run
this by clang-format?

[Dan Beam, 2016/11/17 02:51:47]

Done.

+  ResolveJavascriptCallback(*callback_id, dict);
+}
+
+}  // namespace settings