Mac/clang: Possibly contentious changes.

chrome/browser/cocoa/extensions/browser_action_button.mm

Index: chrome/browser/cocoa/extensions/browser_action_button.mm
diff --git a/chrome/browser/cocoa/extensions/browser_action_button.mm b/chrome/browser/cocoa/extensions/browser_action_button.mm
index cb3c8d6e3bb01e39cb35f236b74cfb4cac12b9a1..914f11d67b148231eeea201ddf02874689d0ade4 100644
--- a/chrome/browser/cocoa/extensions/browser_action_button.mm
+++ b/chrome/browser/cocoa/extensions/browser_action_button.mm
@@ -25,12 +25,12 @@
 #include "skia/ext/skia_utils_mac.h"
 #import "third_party/GTM/AppKit/GTMNSAnimation+Duration.h"
 
-extern const NSString* kBrowserActionButtonUpdatedNotification =
+NSString* const kBrowserActionButtonUpdatedNotification =
     @"BrowserActionButtonUpdatedNotification";
 
-extern const NSString* kBrowserActionButtonDraggingNotification =
+NSString* const kBrowserActionButtonDraggingNotification =
     @"BrowserActionButtonDraggingNotification";
-extern const NSString* kBrowserActionButtonDragEndNotification =
+NSString* const kBrowserActionButtonDragEndNotification =
     @"BrowserActionButtonDragEndNotification";
 
 static const CGFloat kBrowserActionBadgeOriginYOffset = 5;