Have ScopedClipboardWriter and Clipboard::WriteObjects take a buffer parameter.

ui/base/clipboard/clipboard_mac.mm

Index: ui/base/clipboard/clipboard_mac.mm
diff --git a/ui/base/clipboard/clipboard_mac.mm b/ui/base/clipboard/clipboard_mac.mm
index c4671a1eed58340415631c2e99a5acda7ab24267..e3b97cd3e5f3e5965bb8a2fab03b00c59cd89ac6 100644
--- a/ui/base/clipboard/clipboard_mac.mm
+++ b/ui/base/clipboard/clipboard_mac.mm
@@ -84,7 +84,9 @@ Clipboard::Clipboard() {
 Clipboard::~Clipboard() {
 }
 
-void Clipboard::WriteObjects(const ObjectMap& objects) {
+void Clipboard::WriteObjects(Buffer buffer, const ObjectMap& objects) {
+  DCHECK_EQ(buffer, BUFFER_STANDARD);
+
   NSPasteboard* pb = GetPasteboard();
   [pb declareTypes:[NSArray array] owner:nil];