Enable AutoResize for Constrained Web Dialogs for Mac.

chrome/browser/ui/cocoa/login_prompt_cocoa.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/login_prompt_cocoa.h"
 
 #include "base/mac/bundle_locations.h"
 #include "base/mac/scoped_nsobject.h"
 #include "base/strings/string16.h"
 #include "base/strings/string_util.h"
@@ skipping 59 matching lines @@
     // or CancelAuth (say, if the request was cancelled before the UI thread got
     // control).  However, that's OK since any UI interaction in those functions
     // will occur via an InvokeLater on the UI thread, which is guaranteed
     // to happen after this is called (since this was InvokeLater'd first).
     WebContents* requesting_contents = GetWebContentsForLogin();
     DCHECK(requesting_contents);
 
     base::scoped_nsobject<CustomConstrainedWindowSheet> sheet(
         [[CustomConstrainedWindowSheet alloc]
             initWithCustomWindow:[sheet_controller_ window]]);
-    constrained_window_.reset(new ConstrainedWindowMac(
+    constrained_window_.reset(CreateAndShowWebModalDialogMac(
         this, requesting_contents, sheet));
 
     NotifyAuthNeeded();
   }
 
   void CloseDialog() override {
     // The hosting dialog may have been freed.
     if (constrained_window_)
       constrained_window_->CloseWebContentsModalDialog();
   }
@@ skipping 96 matching lines @@
   // Resize the text field.
   CGFloat windowDelta = [GTMUILocalizerAndLayoutTweaker
        sizeToFitFixedWidthTextField:explanationField_];
 
   NSRect newFrame = [[self window] frame];
   newFrame.size.height += windowDelta;
   [[self window] setFrame:newFrame display:NO];
 }
 
 @end