Make aura_demo work on Mac

ui/base/clipboard/clipboard_aura.cc

 // 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.
 
 #include "ui/base/clipboard/clipboard.h"
 
 #include <list>
 
 #include "base/basictypes.h"
 #include "base/files/file_path.h"
@@ skipping 29 matching lines @@
 // It mostly just provides APIs to cleanly access and manipulate this data.
 class ClipboardData {
  public:
   ClipboardData()
       : web_smart_paste_(false),
         format_(0) {}
 
   virtual ~ClipboardData() {}
 
   // Bitmask of AuraClipboardFormat types.
-  const int format() const { return format_; }
+  int format() const { return format_; }
 
   const std::string& text() const { return text_; }
   void set_text(const std::string& text) {
     text_ = text;
     format_ |= TEXT;
   }
 
   const std::string& markup_data() const { return markup_data_; }
   void set_markup_data(const std::string& markup_data) {
     markup_data_ = markup_data;
@@ skipping 603 matching lines @@
   return type;
 }
 
 // static
 const Clipboard::FormatType& Clipboard::GetPepperCustomDataFormatType() {
   CR_DEFINE_STATIC_LOCAL(FormatType, type, (kMimeTypePepperCustomData));
   return type;
 }
 
 }  // namespace ui