Mac: the return of the tab-modal-sheets patch.

chrome/browser/tab_contents/constrained_window.h

 // Copyright (c) 2006-2008 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.
 
 #ifndef CHROME_BROWSER_TAB_CONTENTS_CONSTRAINED_WINDOW_H_
 #define CHROME_BROWSER_TAB_CONTENTS_CONSTRAINED_WINDOW_H_
 
 #include "build/build_config.h"
 
 // The different platform specific subclasses use different delegates for their
@@ skipping 23 matching lines @@
  public:
   // Create a Constrained Window that contains a platform specific client
   // area. Typical uses include the HTTP Basic Auth prompt. The caller must
   // provide a delegate to describe the content area and to respond to events.
   static ConstrainedWindow* CreateConstrainedDialog(
       TabContents* owner,
       ConstrainedWindowDelegate* delegate);
 
   // Closes the Constrained Window.
   virtual void CloseConstrainedWindow() = 0;
+
+  // Events which constrained windows may recognize.
+  enum Event {
+    kEventNavigate,
+  };
+
+  // Inform the constrained the window that its parent tab will do something.
+  // Returns |true| if it did something in response, |false| if not. The default
+  // implementation, appropriate for "content-area" constrained windows, does
+  // the following:
+  //  - |kEventNavigate|: calls |CloseConstrainedWindow()|;
+  //  - anything/everything else: nothing.
+  // Platforms which implement non-"content-area" constrained windows (e.g.,
+  // tab-modal open/close dialogs) should override this.
+  virtual bool ParentWillDo(Event event);
 };
 
 #endif  // CHROME_BROWSER_TAB_CONTENTS_CONSTRAINED_WINDOW_H_