Fix "unused variable" warnings.

content/shell/browser/shell_javascript_dialog_mac.mm

 // Copyright 2013 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 "content/shell/browser/shell_javascript_dialog.h"
 
 #import <Cocoa/Cocoa.h>
 
 #import "base/mac/scoped_nsobject.h"
 #include "base/strings/sys_string_conversions.h"
@@ skipping 75 matching lines @@
 
 namespace content {
 
 ShellJavaScriptDialog::ShellJavaScriptDialog(
     ShellJavaScriptDialogManager* manager,
     gfx::NativeWindow parent_window,
     JavaScriptMessageType message_type,
     const base::string16& message_text,
     const base::string16& default_prompt_text,
     const JavaScriptDialogManager::DialogClosedCallback& callback)
-    : manager_(manager),
-      callback_(callback) {
+    : callback_(callback) {
   bool text_field = message_type == JAVASCRIPT_MESSAGE_TYPE_PROMPT;
   bool one_button = message_type == JAVASCRIPT_MESSAGE_TYPE_ALERT;
 
   helper_ =
       [[ShellJavaScriptDialogHelper alloc] initHelperWithManager:manager
                                                      andCallback:callback];
 
   // Show the modal dialog.
   NSAlert* alert = [helper_ alert];
   NSTextField* field = nil;
@@ skipping 19 matching lines @@
 
 ShellJavaScriptDialog::~ShellJavaScriptDialog() {
   [helper_ release];
 }
 
 void ShellJavaScriptDialog::Cancel() {
   [helper_ cancel];
 }
 
 }  // namespace content