Fix reading PDF images from NSPasteboard.

ui/base/clipboard/clipboard_mac.h

Index: ui/base/clipboard/clipboard_mac.h
diff --git a/ui/base/clipboard/clipboard_mac.h b/ui/base/clipboard/clipboard_mac.h
index 2e264cb0171966e4891200c58d4b276dd01df703..76701ff094b8b0acd1cbfb164134a621b138d2a8 100644
--- a/ui/base/clipboard/clipboard_mac.h
+++ b/ui/base/clipboard/clipboard_mac.h
@@ -21,6 +21,8 @@ class UI_BASE_EXPORT ClipboardMac : public Clipboard {
  private:
   FRIEND_TEST_ALL_PREFIXES(ClipboardMacTest, ReadImageRetina);
   FRIEND_TEST_ALL_PREFIXES(ClipboardMacTest, ReadImageNonRetina);
+  FRIEND_TEST_ALL_PREFIXES(ClipboardMacTest, EmptyImage);
+  FRIEND_TEST_ALL_PREFIXES(ClipboardMacTest, PDFImage);
   friend class Clipboard;
 
   ClipboardMac();