Linux: Add some CHECKs to figure out a crash.

chrome/browser/tab_contents/web_drag_dest_gtk.cc

 // Copyright (c) 2011 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/tab_contents/web_drag_dest_gtk.h"
 
 #include <string>
 
 #include "base/file_path.h"
 #include "base/message_loop.h"
@@ skipping 72 matching lines @@
   if (context_) {
     is_drop_target_ = operation != WebDragOperationNone;
     gdk_drag_status(context_, gtk_util::WebDragOpToGdkDragAction(operation),
                     drag_over_time_);
   }
 }
 
 void WebDragDestGtk::DragLeave() {
   tab_contents_->render_view_host()->DragTargetDragLeave();
 
-  DCHECK(tab_);
+  // TODO(thestig) Turn back to DCHECKs after we figure out bug 89388.
+  CHECK(tab_);
+  CHECK(tab_->bookmark_tab_helper());
   if (tab_->bookmark_tab_helper()->GetBookmarkDragDelegate()) {
     tab_->bookmark_tab_helper()->GetBookmarkDragDelegate()->OnDragLeave(
         bookmark_drag_data_);
   }
 }
 
 gboolean WebDragDestGtk::OnDragMotion(GtkWidget* sender,
                                       GdkDragContext* context,
                                       gint x, gint y,
                                       guint time) {
@@ skipping 192 matching lines @@
   if (browser)
     browser->window()->Show();
 
   // The second parameter is just an educated guess as to whether or not the
   // drag succeeded, but at least we will get the drag-end animation right
   // sometimes.
   gtk_drag_finish(context, is_drop_target_, FALSE, time);
 
   return TRUE;
 }