[Reland] Enable AutoResize for Constrained Web Dialogs for Mac.

chrome/browser/ui/cocoa/extensions/extension_install_dialog_controller.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.
 
 #import "chrome/browser/ui/cocoa/extensions/extension_install_dialog_controller.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/callback_helpers.h"
@@ skipping 42 matching lines @@
             navigator:show_params->GetParentWebContents()
              delegate:this
                prompt:std::move(prompt)]);
 
   base::scoped_nsobject<NSWindow> window([[ConstrainedWindowCustomWindow alloc]
       initWithContentRect:[[view_controller_ view] bounds]]);
   [[window contentView] addSubview:[view_controller_ view]];
 
   base::scoped_nsobject<CustomConstrainedWindowSheet> sheet(
       [[CustomConstrainedWindowSheet alloc] initWithCustomWindow:window]);
-  constrained_window_.reset(new ConstrainedWindowMac(
-      this, show_params->GetParentWebContents(), sheet));
+  constrained_window_ = CreateAndShowWebModalDialogMac(
+      this, show_params->GetParentWebContents(), sheet);
 
   std::string event_name = ExperienceSamplingEvent::kExtensionInstallDialog;
   event_name.append(
       ExtensionInstallPrompt::PromptTypeToString(promptType));
   sampling_event_ = ExperienceSamplingEvent::Create(event_name);
 }
 
 ExtensionInstallDialogController::~ExtensionInstallDialogController() {
 }
 
@@ skipping 28 matching lines @@
     sampling_event_->CreateUserDecisionEvent(decision_event);
   base::ResetAndReturn(&done_callback_).Run(result);
   constrained_window_->CloseWebContentsModalDialog();
 }
 
 // static
 ExtensionInstallPrompt::ShowDialogCallback
 ExtensionInstallPrompt::GetDefaultShowDialogCallback() {
   return base::Bind(&ShowExtensionInstallDialogImpl);
 }