Created min size for print preview dialog and modified to allow the

chrome/browser/ui/webui/constrained_web_dialog_ui.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 CHROME_BROWSER_UI_WEBUI_CONSTRAINED_WEB_DIALOG_UI_H_
 #define CHROME_BROWSER_UI_WEBUI_CONSTRAINED_WEB_DIALOG_UI_H_
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "content/public/browser/web_ui_controller.h"
@@ skipping 83 matching lines @@
 // of a ConstrainedWebDialogUI object.
 // |browser_context| is used to construct the constrained HTML dialog's
 //                   WebContents.
 // |delegate| controls the behavior of the dialog.
 // |overshadowed| is the tab being overshadowed by the dialog.
 ConstrainedWebDialogDelegate* ShowConstrainedWebDialog(
     content::BrowserContext* browser_context,
     ui::WebDialogDelegate* delegate,
     content::WebContents* overshadowed);
 
+ConstrainedWebDialogDelegate* ShowTopLevelConstrainedWebDialog(

[Lei Zhang, 2016/07/25 21:35:10]

Please add a comment similiar to the functions above/below to explain what it
does. All 3 can probably use comments saying "The returned object deletes itself
when the dialog closes."

[rbpotter, 2016/07/26 21:48:19]

Done.

+    content::BrowserContext* browser_context,
+    ui::WebDialogDelegate* delegate,
+    content::WebContents* web_contents);
+
 // Create and show a constrained HTML dialog with auto-resize enabled. The
 // dialog is shown automatically after document load has completed to avoid UI
 // jankiness.
 // |browser_context| is used to construct the dialog's WebContents.
 // |delegate| controls the behavior of the dialog.
 // |overshadowed| is the tab being overshadowed by the dialog.
 // |min_size| is the minimum size of the dialog.
 // |max_size| is the maximum size of the dialog.
 ConstrainedWebDialogDelegate* ShowConstrainedWebDialogWithAutoResize(
     content::BrowserContext* browser_context,
     ui::WebDialogDelegate* delegate,
     content::WebContents* overshadowed,
     const gfx::Size& min_size,
     const gfx::Size& max_size);
 
 #endif  // CHROME_BROWSER_UI_WEBUI_CONSTRAINED_WEB_DIALOG_UI_H_