Fix the crash that could occur when the window is closed while web contents drag is in progress.

content/browser/web_contents/web_contents_view_gtk.cc

Index: content/browser/web_contents/web_contents_view_gtk.cc
diff --git a/content/browser/web_contents/web_contents_view_gtk.cc b/content/browser/web_contents/web_contents_view_gtk.cc
index 1a93e75b0f3fd55365b0f64f8167a3df9d91243b..20b1239bd03260a2254eafe55e0dabce942b109a 100644
--- a/content/browser/web_contents/web_contents_view_gtk.cc
+++ b/content/browser/web_contents/web_contents_view_gtk.cc
@@ -242,13 +242,6 @@ void WebContentsViewGtk::RestoreFocus() {
     SetInitialFocus();
 }
 
-bool WebContentsViewGtk::IsDoingDrag() const {
-  return false;
-}
-
-void WebContentsViewGtk::CancelDragAndCloseTab() {
-}
-
 WebDropData* WebContentsViewGtk::GetDropData() const {
   return drag_dest_->current_drop_data();
 }