JavaScript dialogs cause a page to lose fullscreen.

chrome/browser/printing/print_view_manager.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/printing/print_view_manager.h"
 
 #include <map>
 #include <utility>
 
 #include "base/bind.h"
@@ skipping 202 matching lines @@
   if (rfh != print_preview_rfh_)
     return;
 
   PrintPreviewDialogController* dialog_controller =
       PrintPreviewDialogController::GetInstance();
   if (!dialog_controller) {
     PrintPreviewDone();
     return;
   }
 
+  // Running a dialog causes an exit to webpage-initiated fullscreen.
+  // http://crbug.com/728276
+  if (web_contents()->IsFullscreenForCurrentTab())
+    web_contents()->ExitFullscreen(true);
+
   dialog_controller->PrintPreview(web_contents());
   PrintHostMsg_RequestPrintPreview_Params params;
   params.is_modifiable = source_is_modifiable;
   PrintPreviewUI::SetInitialParams(
       dialog_controller->GetPrintPreviewForContents(web_contents()), params);
 }
 
 void PrintViewManager::OnScriptedPrintPreviewReply(IPC::Message* reply_msg) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
   print_preview_rfh_->Send(reply_msg);
@@ skipping 10 matching lines @@
     IPC_MESSAGE_HANDLER(PrintHostMsg_ShowScriptedPrintPreview,
                         OnShowScriptedPrintPreview)
     IPC_MESSAGE_UNHANDLED(handled = false)
   IPC_END_MESSAGE_MAP()
 
   return handled ||
          PrintViewManagerBase::OnMessageReceived(message, render_frame_host);
 }
 
 }  // namespace printing