extensions: Use stl utilities from the base namespace

extensions/common/message_bundle.cc

Index: extensions/common/message_bundle.cc
diff --git a/extensions/common/message_bundle.cc b/extensions/common/message_bundle.cc
index 104bbae1be9d4f89ee4e7235f1886a519b62af7b..28d7098d641461c78b1810abf64d554dffc422a7 100644
--- a/extensions/common/message_bundle.cc
+++ b/extensions/common/message_bundle.cc
@@ -116,7 +116,7 @@ bool MessageBundle::AppendReservedMessagesForLocale(
   // Add all reserved messages to the dictionary, but check for collisions.
   SubstitutionMap::iterator it = append_messages.begin();
   for (; it != append_messages.end(); ++it) {
-    if (ContainsKey(dictionary_, it->first)) {
+    if (base::ContainsKey(dictionary_, it->first)) {
       *error = ErrorUtils::FormatErrorMessage(
           errors::kReservedMessageFound, it->first);
       return false;