Add WebDragData to blink::WebView::dragtargetDrop

content/renderer/drop_data_builder.cc

Index: content/renderer/drop_data_builder.cc
diff --git a/content/renderer/drop_data_builder.cc b/content/renderer/drop_data_builder.cc
index e10d8d798788b9e2289cd674d95d38aa2e70eeb1..47f0c12b05b244ce2b9fc1f0da8cf8a398095ae5 100644
--- a/content/renderer/drop_data_builder.cc
+++ b/content/renderer/drop_data_builder.cc
@@ -37,7 +37,15 @@ DropData DropDataBuilder::Build(const WebDragData& drag_data) {
           break;
         }
         if (base::EqualsASCII(str_type, ui::Clipboard::kMimeTypeURIList)) {
-          result.url = blink::WebStringToGURL(item.stringData);
+          // The url in WebDragData received could be empty at DragEnter time,

[dcheng, 2016/06/15 12:00:39]

Let's do this this when we convert DropData::Metadata -> WebDragData so we don't
have to do an isEmpty() check here (since it's possible, though odd, for JS to
place an empty URL in the clipboard).

[hush (inactive), 2016/06/15 18:02:59]

Done.

+          // because the URL is not available at DragEnter. We need to convert
+          // to a dummy URL instead of an empty URL, because the latter means
+          // "no URL is in DropData".
+          if (item.stringData.isEmpty()) {
+            result.url = GURL("about:dragdrop-placeholder");
+          } else {
+            result.url = blink::WebStringToGURL(item.stringData);
+          }
           result.url_title = item.title;
           break;
         }