[Extensions] Fix a data race in ChromeExtensionMessageFilter.

extensions/browser/info_map.cc

Index: extensions/browser/info_map.cc
diff --git a/extensions/browser/info_map.cc b/extensions/browser/info_map.cc
index c97832ca4b29d8d86b1bff953726ab4a9c272c65..49ea64329bf5e2369e5473d7f6b8f12dcf5db273 100644
--- a/extensions/browser/info_map.cc
+++ b/extensions/browser/info_map.cc
@@ -49,6 +49,15 @@ InfoMap::ExtraData::~ExtraData() {}
 InfoMap::InfoMap() {
 }
 
+const ExtensionSet& InfoMap::extensions() const {
+  CheckOnValidThread();
+  return extensions_;
+}
+const ExtensionSet& InfoMap::disabled_extensions() const {
+  CheckOnValidThread();
+  return disabled_extensions_;
+}
+
 void InfoMap::AddExtension(const Extension* extension,
                            base::Time install_time,
                            bool incognito_enabled,