RenderWidget popup should be a NSWindow so it can go outside the main window.

content/port/browser/render_widget_host_view_port.h

 // 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.
 
 #ifndef CONTENT_PORT_BROWSER_RENDER_WIDGET_HOST_VIEW_PORT_H_
 #define CONTENT_PORT_BROWSER_RENDER_WIDGET_HOST_VIEW_PORT_H_
 
 #include "base/callback.h"
 #include "base/process_util.h"
 #include "base/string16.h"
@@ skipping 25 matching lines @@
 }
 #endif
 
 namespace skia {
 class PlatformBitmap;
 };
 
 namespace content {
 class BackingStore;
 class SmoothScrollGesture;
+class WebContentsViewDelegate;
 struct NativeWebKeyboardEvent;
 
 // This is the larger RenderWidgetHostView interface exposed only
 // within content/ and to embedders looking to port to new platforms.
 // RenderWidgetHostView class hierarchy described in render_widget_host_view.h.
 class CONTENT_EXPORT RenderWidgetHostViewPort : public RenderWidgetHostView {
  public:
   virtual ~RenderWidgetHostViewPort() {}
 
   // Does the cast for you.
   static RenderWidgetHostViewPort* FromRWHV(RenderWidgetHostView* rwhv);
 
   // Like RenderWidgetHostView::CreateViewForWidget, with cast.
   static RenderWidgetHostViewPort* CreateViewForWidget(
       RenderWidgetHost* widget);
 
   // Perform all the initialization steps necessary for this object to represent
   // a popup (such as a <select> dropdown), then shows the popup at |pos|.
   virtual void InitAsPopup(RenderWidgetHostView* parent_host_view,
-                           const gfx::Rect& pos) = 0;
+                           const gfx::Rect& pos,
+                           WebContentsViewDelegate* delegate = NULL) = 0;
 
   // Perform all the initialization steps necessary for this object to represent
   // a full screen window.
   // |reference_host_view| is the view associated with the creating page that
   // helps to position the full screen widget on the correct monitor.
   virtual void InitAsFullscreen(
       RenderWidgetHostView* reference_host_view) = 0;
 
   // Notifies the View that it has become visible.
   virtual void WasShown() = 0;
@@ skipping 218 matching lines @@
   virtual BrowserAccessibilityManager*
       GetBrowserAccessibilityManager() const = 0;
   virtual void OnAccessibilityNotifications(
       const std::vector<AccessibilityHostMsg_NotificationParams>& params) {
   }
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PORT_BROWSER_RENDER_WIDGET_HOST_VIEW_PORT_H_