Add DCHECK to MaskedViewTargeter::GetHitTestMask() overrides

chrome/browser/ui/views/tabs/tab_strip.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 "chrome/browser/ui/views/tabs/tab_strip.h"
 
 #if defined(OS_WIN)
 #include <windowsx.h>
 #endif
 
@@ skipping 412 matching lines @@
  public:
   explicit NewTabButtonTargeter(views::View* new_tab_button)
       : views::MaskedViewTargeter(new_tab_button) {}
   virtual ~NewTabButtonTargeter() {}
 
  private:
   // views::MaskedViewTargeter:
   virtual bool GetHitTestMask(const views::View* view,
                               gfx::Path* mask) const OVERRIDE {
     DCHECK(mask);
+    DCHECK_EQ(view, masked_view());
 
     SkScalar w = SkIntToScalar(view->width());
     SkScalar v_offset = SkIntToScalar(kNewTabButtonVerticalOffset);
 
     // These values are defined by the shape of the new tab image. Should that
     // image ever change, these values will need to be updated. They're so
     // custom it's not really worth defining constants for.
     // These values are correct for regular and USE_ASH versions of the image.
     mask->moveTo(0, v_offset + 1);
     mask->lineTo(w - 7, v_offset + 1);
@@ skipping 2218 matching lines @@
   if (value == reset_to_shrink_on_exit_)
     return;
 
   reset_to_shrink_on_exit_ = value;
   // Add an observer so we know when the mouse moves out of the tabstrip.
   if (reset_to_shrink_on_exit_)
     AddMessageLoopObserver();
   else
     RemoveMessageLoopObserver();
 }