Initialize dragged tab backing store to null....

chrome/browser/gtk/tabs/dragged_tab_gtk.cc

 // Copyright (c) 2009 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 "chrome/browser/gtk/tabs/dragged_tab_gtk.h"
 
 #include <gdk/gdk.h>
 
 #include <algorithm>
 
@@ skipping 21 matching lines @@
 const SkColor kDraggedTabBorderColor = SkColorSetRGB(103, 129, 162);
 
 }  // namespace
 
 ////////////////////////////////////////////////////////////////////////////////
 // DraggedTabGtk, public:
 
 DraggedTabGtk::DraggedTabGtk(TabContents* datasource,
                              const gfx::Point& mouse_tab_offset,
                              const gfx::Size& contents_size)
-    : renderer_(new TabRendererGtk),
+    : backing_store_(NULL),
+      renderer_(new TabRendererGtk),
       attached_(false),
       mouse_tab_offset_(mouse_tab_offset),
       attached_tab_size_(TabRendererGtk::GetMinimumSelectedSize()),
       contents_size_(contents_size),
       close_animation_(this) {
   renderer_->UpdateData(datasource, false);
 
   container_ = gtk_window_new(GTK_WINDOW_POPUP);
   SetContainerColorMap();
   gtk_widget_set_app_paintable(container_, TRUE);
@@ skipping 261 matching lines @@
   } else {
     dragged_tab->SetContainerShapeMask(bmp);
   }
 
   gfx::CanvasPaint canvas(event, false);
   canvas.DrawBitmapInt(bmp, 0, 0);
 
   // We've already drawn the tab, so don't propagate the expose-event signal.
   return TRUE;
 }