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

content/browser/renderer_host/render_widget_host_view_guest.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/bind_helpers.h"
 #include "base/logging.h"
 #include "base/message_loop.h"
 #include "content/browser/browser_plugin/browser_plugin_guest.h"
 #include "content/browser/renderer_host/render_view_host_impl.h"
 #include "content/browser/renderer_host/render_widget_host_view_guest.h"
@@ skipping 89 matching lines @@
 void RenderWidgetHostViewGuest::SetBounds(const gfx::Rect& rect) {
   SetSize(rect.size());
 }
 
 void RenderWidgetHostViewGuest::InitAsChild(
     gfx::NativeView parent_view) {
   NOTIMPLEMENTED();
 }
 
 void RenderWidgetHostViewGuest::InitAsPopup(
-    RenderWidgetHostView* parent_host_view, const gfx::Rect& pos) {
+    RenderWidgetHostView* parent_host_view, const gfx::Rect& pos,
+    WebContentsViewDelegate*) {
   NOTIMPLEMENTED();
 }
 
 void RenderWidgetHostViewGuest::InitAsFullscreen(
     RenderWidgetHostView* reference_host_view) {
   NOTIMPLEMENTED();
 }
 
 gfx::NativeView RenderWidgetHostViewGuest::GetNativeView() const {
   NOTIMPLEMENTED();
@@ skipping 279 matching lines @@
 }
 #endif
 
 #if defined(OS_POSIX) || defined(USE_AURA)
 void RenderWidgetHostViewGuest::GetScreenInfo(WebKit::WebScreenInfo* results) {
   NOTIMPLEMENTED();
 }
 #endif  // defined(OS_POSIX) || defined(USE_AURA)
 
 }  // namespace content