Namespace comments fixes in /extension/commons to comply Chrome style standards.

Changes:
1) dom_action_types.h
2) install_warning.h

Review URL: https://codereview.chromium.org/296173011

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@272847 0039d316-1c4b-4281-b951-d872f2087c98

extensions/common/dom_action_types.h

@@ -21,6 +21,6 @@ struct DomActionType {
   };
 };
 
-}  // namespace
+}  // namespace extensions
 
 #endif  // EXTENSIONS_COMMON_DOM_ACTION_TYPES_H_

extensions/common/install_warning.h

@@ -43,6 +43,6 @@ struct InstallWarning {
 // Let gtest print InstallWarnings.
 void PrintTo(const InstallWarning&, ::std::ostream* os);
 
-}  // namespace
+}  // namespace extensions
 
 #endif  // EXTENSIONS_COMMON_INSTALL_WARNING_H_