Added usage of ScreenContext in EulaScreen.

chrome/browser/chromeos/login/screens/base_screen.cc

Index: chrome/browser/chromeos/login/screens/base_screen.cc
diff --git a/chrome/browser/chromeos/login/screens/base_screen.cc b/chrome/browser/chromeos/login/screens/base_screen.cc
index 82f38861ed19d96d9a7870e0b69cc4ff17a89110..cd97e2afb68574e015acc198d5069b3881cfe614 100644
--- a/chrome/browser/chromeos/login/screens/base_screen.cc
+++ b/chrome/browser/chromeos/login/screens/base_screen.cc
@@ -37,6 +37,8 @@ bool BaseScreen::IsPermanent() {
 }
 
 std::string BaseScreen::GetID() const {
+  // TODO (ygorshenin, crbug.com/433797): elimitate intermediate
+  // GetName() ASAP.
   return GetName();
 }
 
@@ -51,8 +53,16 @@ void BaseScreen::OnButtonPressed(const std::string& button_id) {
   LOG(WARNING) << "BaseScreen::OnButtonPressed(): button_id=" << button_id;
 }
 
-void BaseScreen::OnContextChanged(const base::DictionaryValue* diff) {
-  LOG(WARNING) << "BaseScreen::OnContextChanged()";
+void BaseScreen::OnContextKeyUpdated(
+    const ::login::ScreenContext::KeyType& key) {
+  LOG(WARNING) << "BaseScreen::OnContextKeyUpdated(): key=" << key;

[dzhioev (left Google), 2014/11/27 11:54:02]

Please make the message more meaningful. For example, "Unhandled context change.
Key=...". 

[ygorshenin1, 2014/11/27 13:07:33]

Done.

+}
+
+void BaseScreen::OnContextChanged(const base::DictionaryValue& diff) {
+  std::vector<::login::ScreenContext::KeyType> keys;
+  context_.ApplyChanges(diff, &keys);
+  for (const auto& key : keys)
+    OnContextKeyUpdated(key);
 }
 
 }  // namespace chromeos