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

chrome/browser/printing/print_preview_test.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_PRINTING_PRINT_PREVIEW_TEST_H_
 #define CHROME_BROWSER_PRINTING_PRINT_PREVIEW_TEST_H_
 
 #include "base/macros.h"
+#include "chrome/browser/printing/print_preview_dialog_controller.h"
 #include "chrome/test/base/browser_with_test_window_test.h"
+#include "ui/views/window/dialog_delegate.h"
 
 class PrintPreviewTest : public BrowserWithTestWindowTest {
  public:
   PrintPreviewTest();
   ~PrintPreviewTest() override;
 
  protected:
   void SetUp() override;
 
   // Create a browser window to provide parenting for web contents modal dialog.
   BrowserWindow* CreateBrowserWindow() override;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(PrintPreviewTest);
 };
 
+#if defined(USE_AURA)
+class PrintPreviewDialogControllerTest:
+  public printing::PrintPreviewDialogController {
+ public:
+  explicit PrintPreviewDialogControllerTest(gfx::NativeView context);
+
+  // Need to override the function to get the delegate so that it uses the
+  // correct window.
+  ConstrainedWebDialogDelegate* GetWebDialogDelegate(
+      content::WebContents* initiator) override;
+
+  void SetContext(gfx::NativeView context);
+
+ protected:
+  ~PrintPreviewDialogControllerTest() override;
+
+ private:
+  gfx::NativeView context_;
+
+};
+#endif  // defined(USE_AURA)
+
 #endif  // CHROME_BROWSER_PRINTING_PRINT_PREVIEW_TEST_H_