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

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/web_contents/web_contents_view_gtk.h"
 
 #include <gdk/gdk.h>
 #include <gdk/gdkkeysyms.h>
 #include <gtk/gtk.h>
 
@@ skipping 224 matching lines @@
   focus_store_.Store(GetNativeView());
 }
 
 void WebContentsViewGtk::RestoreFocus() {
   if (focus_store_.widget())
     gtk_widget_grab_focus(focus_store_.widget());
   else
     SetInitialFocus();
 }
 
-bool WebContentsViewGtk::IsDoingDrag() const {
-  return false;
-}
-
-void WebContentsViewGtk::CancelDragAndCloseTab() {
-}
-
 WebDropData* WebContentsViewGtk::GetDropData() const {
   return drag_dest_->current_drop_data();
 }
 
 bool WebContentsViewGtk::IsEventTracking() const {
   return false;
 }
 
 void WebContentsViewGtk::CloseTabAfterEventTracking() {
 }
@@ skipping 126 matching lines @@
   // We manually tell our RWHV to resize the renderer content.  This avoids
   // spurious resizes from GTK+.
   RenderWidgetHostView* rwhv = web_contents_->GetRenderWidgetHostView();
   if (rwhv)
     rwhv->SetSize(size);
   if (web_contents_->GetInterstitialPage())
     web_contents_->GetInterstitialPage()->SetSize(size);
 }
 
 }  // namespace content