Add onChanged events to the extension settings API, both from sync and between

chrome/browser/extensions/extension_settings_storage_cache.cc

Index: chrome/browser/extensions/extension_settings_storage_cache.cc
diff --git a/chrome/browser/extensions/extension_settings_storage_cache.cc b/chrome/browser/extensions/extension_settings_storage_cache.cc
index f20f068f9b7dfbd1f4bcfa7d65ea74195ef1042a..6137c3139266edc8ee3e35a7690961cef350a9b3 100644
--- a/chrome/browser/extensions/extension_settings_storage_cache.cc
+++ b/chrome/browser/extensions/extension_settings_storage_cache.cc
@@ -15,7 +15,7 @@ ExtensionSettingsStorage::Result ExtensionSettingsStorageCache::Get(
   if (GetFromCache(key, &value)) {
     DictionaryValue* settings = new DictionaryValue();
     settings->SetWithoutPathExpansion(key, value);
-    return Result(settings, NULL);
+    return Result(settings, NULL, NULL);
   }
 
   Result result = delegate_->Get(key);
@@ -43,7 +43,7 @@ ExtensionSettingsStorage::Result ExtensionSettingsStorageCache::Get(
   }
 
   if (missing_keys.empty()) {
-    return Result(from_cache.release(), NULL);
+    return Result(from_cache.release(), NULL, NULL);
   }
 
   Result result = delegate_->Get(keys);
@@ -52,8 +52,10 @@ ExtensionSettingsStorage::Result ExtensionSettingsStorageCache::Get(
   }
 
   cache_.MergeDictionary(result.GetSettings());
-  result.GetSettings()->MergeDictionary(from_cache.get());
-  return result;
+
+  DictionaryValue* settings_with_cache = result.GetSettings()->DeepCopy();
+  settings_with_cache->MergeDictionary(from_cache.get());
+  return Result(settings_with_cache, NULL, NULL);
 }
 
 ExtensionSettingsStorage::Result ExtensionSettingsStorageCache::Get() {
@@ -80,7 +82,7 @@ ExtensionSettingsStorage::Result ExtensionSettingsStorageCache::Set(
     return result;
   }
 
-  std::set<std::string>* changed_keys = result.GetChangedKeys();
+  const std::set<std::string>* changed_keys = result.GetChangedKeys();
   DCHECK(changed_keys);
   for (std::set<std::string>::iterator it = changed_keys->begin();
       it != changed_keys->end(); ++it) {
@@ -108,7 +110,7 @@ ExtensionSettingsStorage::Result ExtensionSettingsStorageCache::Remove(
     return result;
   }
 
-  std::set<std::string>* changed_keys = result.GetChangedKeys();
+  const std::set<std::string>* changed_keys = result.GetChangedKeys();
   DCHECK(changed_keys);
   for (std::set<std::string>::iterator it = changed_keys->begin();
       it != changed_keys->end(); ++it) {