Fix print preview dialog for <webview>.

chrome/browser/ui/cocoa/constrained_window/constrained_window_mac.mm

 // 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/cocoa/constrained_window/constrained_window_mac.h"
 
 #include "base/logging.h"
+#include "chrome/browser/guest_view/web_view/web_view_guest.h"
 #include "chrome/browser/ui/browser_finder.h"
 #include "chrome/browser/ui/browser_window.h"
 #import "chrome/browser/ui/cocoa/constrained_window/constrained_window_sheet.h"
 #import "chrome/browser/ui/cocoa/constrained_window/constrained_window_sheet_controller.h"
 #import "chrome/browser/ui/cocoa/tabs/tab_strip_controller.h"
 #include "components/web_modal/web_contents_modal_dialog_manager.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/web_contents.h"
 
 using web_modal::WebContentsModalDialogManager;
 using web_modal::NativeWebContentsModalDialog;
 
 ConstrainedWindowMac::ConstrainedWindowMac(
     ConstrainedWindowMacDelegate* delegate,
     content::WebContents* web_contents,
     id<ConstrainedWindowSheet> sheet)
     : delegate_(delegate),
-      web_contents_(web_contents),
+      web_contents_(NULL),
       sheet_([sheet retain]),
       shown_(false) {
   DCHECK(web_contents);
+  WebViewGuest* web_view_guest = WebViewGuest::FromWebContents(web_contents);
+  // For embedded WebContents, use the embedder's WebContents for constrained
+  // window.
+  web_contents_ = web_view_guest && web_view_guest->embedder_web_contents() ?
+                      web_view_guest->embedder_web_contents() : web_contents;
   DCHECK(sheet_.get());
   WebContentsModalDialogManager* web_contents_modal_dialog_manager =
-      WebContentsModalDialogManager::FromWebContents(web_contents);
+      WebContentsModalDialogManager::FromWebContents(web_contents_);
   web_contents_modal_dialog_manager->ShowModalDialog(this);
 }
 
 ConstrainedWindowMac::~ConstrainedWindowMac() {
   CHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
 }
 
 void ConstrainedWindowMac::ShowWebContentsModalDialog() {
   if (shown_)
     return;
@@ skipping 42 matching lines @@
 
 NSWindow* ConstrainedWindowMac::GetParentWindow() const {
   // Tab contents in a tabbed browser may not be inside a window. For this
   // reason use a browser window if possible.
   Browser* browser = chrome::FindBrowserWithWebContents(web_contents_);
   if (browser)
     return browser->window()->GetNativeWindow();
 
   return web_contents_->GetTopLevelNativeWindow();
 }