Added usage of ScreenContext in EulaScreen.

components/login/screens/screen_context.cc

 // Copyright (c) 2013 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 "components/login/screens/screen_context.h"
 
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 
 namespace login {
@@ skipping 104 matching lines @@
 String16List ScreenContext::GetString16List(const KeyType& key) const {
   return Get<String16List>(key);
 }
 
 String16List ScreenContext::GetString16List(
     const KeyType& key,
     const String16List& default_value) const {
   return Get(key, default_value);
 }
 
+scoped_ptr<ScreenContext::KeyObserverSubscription>
+ScreenContext::AddKeyObserver(const KeyType& key, const KeyObserver& observer) {
+  auto it = key_observers_.find(key);
+  linked_ptr<KeyObserversList> observers_list;
+  if (it == key_observers_.end()) {
+    observers_list.reset(new KeyObserversList());
+    key_observers_[key] = observers_list;
+  } else {
+    observers_list = it->second;
+  }
+  return observers_list->Add(observer);
+}
+
 bool ScreenContext::HasKey(const KeyType& key) const {
   DCHECK(CalledOnValidThread());
   return storage_.HasKey(key);
 }
 
 bool ScreenContext::HasChanges() const {
   DCHECK(CalledOnValidThread());
   return !changes_.empty();
 }
 
 void ScreenContext::GetChangesAndReset(base::DictionaryValue* diff) {
   DCHECK(CalledOnValidThread());
   DCHECK(diff);
   changes_.Swap(diff);
   changes_.Clear();
 }
 
 void ScreenContext::ApplyChanges(const base::DictionaryValue& diff,
                                  std::vector<std::string>* keys) {
   DCHECK(CalledOnValidThread());
   DCHECK(!HasChanges());
   if (keys) {
     keys->clear();
     keys->reserve(diff.size());
   }
-  base::DictionaryValue::Iterator it(diff);
-  while (!it.IsAtEnd()) {
+
+  for (base::DictionaryValue::Iterator it(diff); !it.IsAtEnd(); it.Advance()) {
     Set(it.key(), it.value().DeepCopy());
     if (keys)
       keys->push_back(it.key());
-    it.Advance();
+
+    linked_ptr<KeyObserversList> observers = key_observers_[it.key()];
+    if (observers.get())
+      observers->Notify(it.key(), it.value());
   }
   changes_.Clear();
 }
 
 bool ScreenContext::Set(const KeyType& key, base::Value* value) {
   DCHECK(CalledOnValidThread());
   DCHECK(value);
   scoped_ptr<base::Value> new_value(value);
 
   base::Value* current_value;
   bool in_storage = storage_.Get(key, &current_value);
 
   // Don't do anything if |storage_| already contains <|key|, |new_value|> pair.
   if (in_storage && new_value->Equals(current_value))
     return false;
 
   changes_.Set(key, new_value->DeepCopy());
   storage_.Set(key, new_value.release());
   return true;
 }
 
 }  // namespace login