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 ee3975d5692e9684b861e763e8ef996f0970e964..c639c14e2624fac56c8db3507dc7d497a6a026c3 100644
--- a/ui/base/clipboard/clipboard_aurax11.cc
+++ b/ui/base/clipboard/clipboard_aurax11.cc
@@ -455,7 +455,8 @@ 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);