Mac: Fix SDK 10.11 Compile errors after clang roll in r387792

chrome/browser/ui/cocoa/bookmarks/bookmark_menu_cocoa_controller.mm

Index: chrome/browser/ui/cocoa/bookmarks/bookmark_menu_cocoa_controller.mm
diff --git a/chrome/browser/ui/cocoa/bookmarks/bookmark_menu_cocoa_controller.mm b/chrome/browser/ui/cocoa/bookmarks/bookmark_menu_cocoa_controller.mm
index 529921204815d3b6485d74ebfdf6a68795613481..169beadc9fc97b9c0c270ec4b2a343425fd87655 100644
--- a/chrome/browser/ui/cocoa/bookmarks/bookmark_menu_cocoa_controller.mm
+++ b/chrome/browser/ui/cocoa/bookmarks/bookmark_menu_cocoa_controller.mm
@@ -4,6 +4,7 @@
 
 #import "chrome/browser/ui/cocoa/bookmarks/bookmark_menu_cocoa_controller.h"
 
+#import "base/mac/foundation_util.h"
 #include "base/strings/sys_string_conversions.h"
 #include "chrome/app/chrome_command_ids.h"  // IDC_BOOKMARK_MENU
 #import "chrome/browser/app_controller_mac.h"
@@ -71,7 +72,8 @@ const NSUInteger kMaximumMenuPixelsWide = 300;
 }
 
 - (BOOL)validateMenuItem:(NSMenuItem*)menuItem {
-  AppController* controller = [NSApp delegate];
+  AppController* controller =
+      base::mac::ObjCCastStrict<AppController>([NSApp delegate]);
   return ![controller keyWindowIsModal];
 }