Add base:: namespace to string16 in chrome/browser/extensions.

[email protected]
BUG=none
TEST=compile

Review URL: https://codereview.chromium.org/108813011

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@241260 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/chrome/browser/extensions/extension_message_bubble_controller.cc b/chrome/browser/extensions/extension_message_bubble_controller.cc
index bf7ecc4..1cf7e4fb 100644
--- a/chrome/browser/extensions/extension_message_bubble_controller.cc
+++ b/chrome/browser/extensions/extension_message_bubble_controller.cc
@@ -44,13 +44,13 @@
   return !GetOrCreateExtensionList()->empty();
 }
 
-std::vector<string16>
+std::vector<base::string16>
 ExtensionMessageBubbleController::GetExtensionList() {
   ExtensionIdList* list = GetOrCreateExtensionList();
   if (list->empty())
-    return std::vector<string16>();
+    return std::vector<base::string16>();
 
-  std::vector<string16> return_value;
+  std::vector<base::string16> return_value;
   for (ExtensionIdList::const_iterator it = list->begin();
        it != list->end(); ++it) {
     const Extension* extension = service_->GetInstalledExtension(*it);