Set the initial dialog width when the sign-in email confirmation dialog is presented.

chrome/browser/ui/webui/signin/signin_email_confirmation_dialog.cc

 // Copyright 2016 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/signin/signin_email_confirmation_dialog.h"
 
 #include <vector>
 
 #include "base/json/json_reader.h"
 #include "base/json/json_writer.h"
@@ skipping 122 matching lines @@
 }
 
 GURL SigninEmailConfirmationDialog::GetDialogContentURL() const {
   return GURL(chrome::kChromeUISigninEmailConfirmationURL);
 }
 
 void SigninEmailConfirmationDialog::GetWebUIMessageHandlers(
     std::vector<content::WebUIMessageHandler*>* handlers) const {}
 
 void SigninEmailConfirmationDialog::GetDialogSize(gfx::Size* size) const {
-  // Avoid setting a dialog size in here as this dialog auto-resizes (see
-  // method |SigninEmailConfirmationDialog::Show|.
+  DCHECK(size);
+
+  // Set the dialog width if it's not set, so that the dialog is center-aligned
+  // horizontally when it appears. Avoid setting a dialog height in here as
+  // this dialog auto-resizes.
+  if (size->IsEmpty())
+    size->set_width(kDialogWidth);
 }
 
 std::string SigninEmailConfirmationDialog::GetDialogArgs() const {
   std::string data;
   base::DictionaryValue dialog_args;
   dialog_args.SetString("lastEmail", last_email_);
   dialog_args.SetString("newEmail", new_email_);
   base::JSONWriter::Write(dialog_args, &data);
   return data;
 }
@@ skipping 32 matching lines @@
 
 void SigninEmailConfirmationDialog::OnCloseContents(
     content::WebContents* source,
     bool* out_close_dialog) {
   *out_close_dialog = true;
 }
 
 bool SigninEmailConfirmationDialog::ShouldShowDialogTitle() const {
   return false;
 }