Example of usage of new features of context and screen.

chrome/browser/ui/webui/chromeos/login/controller_pairing_screen_handler.cc

Index: chrome/browser/ui/webui/chromeos/login/controller_pairing_screen_handler.cc
diff --git a/chrome/browser/ui/webui/chromeos/login/controller_pairing_screen_handler.cc b/chrome/browser/ui/webui/chromeos/login/controller_pairing_screen_handler.cc
new file mode 100644
index 0000000000000000000000000000000000000000..01b0092f564b3953876edbedbb90af0e5ac93440
--- /dev/null
+++ b/chrome/browser/ui/webui/chromeos/login/controller_pairing_screen_handler.cc
@@ -0,0 +1,93 @@
+// Copyright 2014 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/chromeos/login/controller_pairing_screen_handler.h"
+
+#include "chrome/browser/ui/webui/chromeos/login/oobe_ui.h"
+#include "content/public/browser/web_contents.h"
+
+namespace chromeos {
+
+namespace {
+
+const char kJsScreenPath[] = "login.ControllerPairingScreen";
+
+const char kMethodContextChanged[] = "contextChanged";
+
+const char kCallbackButtonClicked[] = "buttonClicked";
+const char kCallbackContextChanged[] = "contextChanged";
+
+}  // namespace
+
+ControllerPairingScreenHandler::ControllerPairingScreenHandler()
+    : BaseScreenHandler(kJsScreenPath), delegate_(NULL), show_on_init_(false) {
+}
+
+ControllerPairingScreenHandler::~ControllerPairingScreenHandler() {
+  if (delegate_)
+    delegate_->OnActorDestroyed(this);
+}
+
+void ControllerPairingScreenHandler::HandleButtonClicked(
+    const std::string& action) {
+  if (!delegate_)
+    return;
+  delegate_->OnButtonClicked(action);
+}
+
+void ControllerPairingScreenHandler::HandleContextChanged(
+    const base::DictionaryValue* diff) {
+  if (!delegate_)
+    return;
+  delegate_->OnScreenContextChanged(*diff);
+}
+
+void ControllerPairingScreenHandler::Initialize() {
+  if (!page_is_ready() || !delegate_)
+    return;
+
+  if (show_on_init_) {
+    Show();
+    show_on_init_ = false;
+  }
+}
+
+void ControllerPairingScreenHandler::DeclareLocalizedValues(
+    LocalizedValuesBuilder* builder) {
+}
+
+void ControllerPairingScreenHandler::RegisterMessages() {
+  AddPrefixedCallback(kCallbackButtonClicked,
+                      &ControllerPairingScreenHandler::HandleButtonClicked);
+  AddPrefixedCallback(kCallbackContextChanged,
+                      &ControllerPairingScreenHandler::HandleContextChanged);
+}
+
+void ControllerPairingScreenHandler::Show() {
+  if (!page_is_ready()) {
+    show_on_init_ = true;
+    return;
+  }
+  ShowScreen(OobeUI::kScreenControllerPairing, NULL);
+}
+
+void ControllerPairingScreenHandler::Hide() {
+}
+
+void ControllerPairingScreenHandler::SetDelegate(Delegate* delegate) {
+  delegate_ = delegate;
+  if (page_is_ready())
+    Initialize();
+}
+
+void ControllerPairingScreenHandler::OnContextChanged(
+    const base::DictionaryValue& diff) {
+  CallJS(kMethodContextChanged, diff);
+}
+
+content::BrowserContext* ControllerPairingScreenHandler::GetBrowserContext() {
+  return web_ui()->GetWebContents()->GetBrowserContext();
+}
+
+}  // namespace chromeos