We have a problem in the process on destroying WebContentsImpl because

chrome/browser/printing/print_preview_dialog_controller_browsertest.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 "base/command_line.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/run_loop.h"
 #include "chrome/browser/printing/print_preview_dialog_controller.h"
 #include "chrome/browser/ui/browser.h"
 #include "chrome/browser/ui/browser_commands.h"
@@ skipping 73 matching lines @@
   explicit PrintPreviewDialogDestroyedObserver(WebContents* dialog)
       : WebContentsObserver(dialog),
         dialog_destroyed_(false) {
   }
   virtual ~PrintPreviewDialogDestroyedObserver() {}
 
   bool dialog_destroyed() const { return dialog_destroyed_; }
 
  private:
   // content::WebContentsObserver implementation.
-  virtual void WebContentsDestroyed(WebContents* contents) OVERRIDE {
+  virtual void WebContentsDestroyed() OVERRIDE {
     dialog_destroyed_ = true;
   }
 
   bool dialog_destroyed_;
 
   DISALLOW_COPY_AND_ASSIGN(PrintPreviewDialogDestroyedObserver);
 };
 
 class PrintPreviewDialogControllerBrowserTest : public InProcessBrowserTest {
  public:
@@ skipping 108 matching lines @@
       browser()->tab_strip_model()->GetActiveWebContents());
   ASSERT_TRUE(dialog_destroyed_observer.dialog_destroyed());
 
   // Try printing again.
   PrintPreview();
 
   // Create a preview dialog for the initiator tab.
   WebContents* new_preview_dialog = GetPrintPreviewDialog();
   EXPECT_TRUE(new_preview_dialog);
 }