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

chrome/browser/ui/webui/media_router/media_router_dialog_controller_impl.cc

 // Copyright 2015 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/webui/media_router/media_router_dialog_controller_impl.h"
 
 #include <memory>
 #include <string>
 #include <utility>
 #include <vector>
@@ skipping 43 matching lines @@
 // will look like.
 class MediaRouterDialogDelegate : public WebDialogDelegate {
  public:
   explicit MediaRouterDialogDelegate(
       const base::WeakPtr<MediaRouterDialogControllerImpl>& controller)
       : controller_(controller) {}
   ~MediaRouterDialogDelegate() override {}
 
   // WebDialogDelegate implementation.
   ui::ModalType GetDialogModalType() const override {
-    // Not used, returning dummy value.
-    return ui::MODAL_TYPE_WINDOW;
+    return ui::MODAL_TYPE_CHILD;
   }
 
   base::string16 GetDialogTitle() const override {
     return base::string16();
   }
 
   GURL GetDialogContentURL() const override {
     return GURL(chrome::kChromeUIMediaRouterURL);
   }
 
@@ skipping 257 matching lines @@
       PresentationServiceDelegateImpl::FromWebContents(initiator());
   if (!create_connection_request.get()) {
     media_router_ui->InitWithDefaultMediaSource(initiator(), delegate);
   } else {
     media_router_ui->InitWithPresentationSessionRequest(
         initiator(), delegate, std::move(create_connection_request));
   }
 }
 
 }  // namespace media_router