Change the ChromiumPasteboard to have a notion of an alternate clipboard...

chrome/browser/renderer_host/render_widget_host_view_gtk.h

Index: chrome/browser/renderer_host/render_widget_host_view_gtk.h
===================================================================
--- chrome/browser/renderer_host/render_widget_host_view_gtk.h	(revision 25640)
+++ chrome/browser/renderer_host/render_widget_host_view_gtk.h	(working copy)
@@ -61,7 +61,6 @@
   virtual void Destroy();
   virtual void SetTooltipText(const std::wstring& tooltip_text);
   virtual void SelectionChanged(const std::string& text);
-  virtual void PasteFromSelectionClipboard();
   virtual void ShowingContextMenu(bool showing);
   virtual BackingStore* AllocBackingStore(const gfx::Size& size);
   virtual void SetBackground(const SkBitmap& background);
@@ -78,12 +77,6 @@
   // Update the display cursor for the render view.
   void ShowCurrentCursor();
 
-  // When we've requested the text from the X clipboard, GTK returns it to us
-  // through this callback.
-  static void ReceivedSelectionText(GtkClipboard* clipboard,
-                                    const gchar* text,
-                                    gpointer userdata);
-
   // The model object.
   RenderWidgetHost* const host_;