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

ui/base/clipboard/clipboard_aurax11.cc

Index: ui/base/clipboard/clipboard_aurax11.cc
diff --git a/ui/base/clipboard/clipboard_aurax11.cc b/ui/base/clipboard/clipboard_aurax11.cc
index 4760aff1254d99af5c15e427e969204ad323f9a3..9a9dde4db4243d114247b344225a5ccd8098afdd 100644
--- a/ui/base/clipboard/clipboard_aurax11.cc
+++ b/ui/base/clipboard/clipboard_aurax11.cc
@@ -456,7 +456,8 @@ Clipboard::~Clipboard() {
   DeleteClipboard();
 }
 
-void Clipboard::WriteObjects(const ObjectMap& objects) {
+void Clipboard::WriteObjects(Buffer buffer, const ObjectMap& objects) {
+  DCHECK(IsValidBuffer(buffer));
   for (ObjectMap::const_iterator iter = objects.begin();
        iter != objects.end(); ++iter) {
     DispatchObject(static_cast<ObjectType>(iter->first), iter->second);