Add WebDragData to blink::WebView::dragtargetDrop

content/public/common/drop_data.h

Index: content/public/common/drop_data.h
diff --git a/content/public/common/drop_data.h b/content/public/common/drop_data.h
index e589184b41f2f0442d065e91faf72d7bebff750b..49724d256327cc83bb3f11d771eba53253bdfd43 100644
--- a/content/public/common/drop_data.h
+++ b/content/public/common/drop_data.h
@@ -38,6 +38,9 @@ struct CONTENT_EXPORT DropData {
   // Whether this drag originated from a renderer.
   bool did_originate_from_renderer;
 
+  // Whether this DropData has been initialized.
+  bool is_valid;
+
   // User is dragging a link into the webview.
   GURL url;
   base::string16 url_title;  // The title associated with |url|.