Add stubs and glue for routing a request for an image from the clipboard.

ui/base/clipboard/clipboard_linux.cc

Index: ui/base/clipboard/clipboard_linux.cc
diff --git a/ui/base/clipboard/clipboard_linux.cc b/ui/base/clipboard/clipboard_linux.cc
index f9ec174418c83a798a2bcf28d249d13ac4b8ff9f..3bb1e888075c2cb37cb3e8e6b423c9152a2cd365 100644
--- a/ui/base/clipboard/clipboard_linux.cc
+++ b/ui/base/clipboard/clipboard_linux.cc
@@ -360,6 +360,15 @@ void Clipboard::ReadHTML(Clipboard::Buffer buffer, string16* markup,
   gtk_selection_data_free(data);
 }
 
+void Clipboard::ReadImage(Buffer buffer, std::string* data) const {
+  // TODO(dcheng): implement this.
+  NOTIMPLEMENTED();
+  if (!data) {
+    NOTREACHED();
+    return;
+  }
+}
+
 void Clipboard::ReadBookmark(string16* title, std::string* url) const {
   // TODO(estade): implement this.
   NOTIMPLEMENTED();