Expose RTF content on the clipboard as strings to pages when pasting.

content/renderer/webclipboard_impl.h

Index: content/renderer/webclipboard_impl.h
diff --git a/content/renderer/webclipboard_impl.h b/content/renderer/webclipboard_impl.h
index 6a3d82b574117086f341603757c07714ce7f4ae1..009980ca2e2f94ec4d42420f6cf4abca901c9f0c 100644
--- a/content/renderer/webclipboard_impl.h
+++ b/content/renderer/webclipboard_impl.h
@@ -33,6 +33,7 @@ class WebClipboardImpl : public blink::WebClipboard {
                             blink::WebURL* source_url,
                             unsigned* fragment_start,
                             unsigned* fragment_end) override;
+  blink::WebString readRTF(Buffer buffer) override;
   blink::WebBlobInfo readImage(Buffer buffer) override;
   blink::WebString readCustomData(Buffer buffer,
                                   const blink::WebString& type) override;