Use extension-based file picker from CrOS for Aura builds.

chrome/browser/extensions/extension_file_browser_private_api.h

 // Copyright (c) 2011 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.
 
 #ifndef CHROME_BROWSER_EXTENSIONS_EXTENSION_FILE_BROWSER_PRIVATE_API_H_
 #define CHROME_BROWSER_EXTENSIONS_EXTENSION_FILE_BROWSER_PRIVATE_API_H_
 #pragma once
 
 #include <map>
 #include <string>
@@ skipping 215 matching lines @@
  protected:
   virtual ~AddMountFunction();
 
   virtual bool RunImpl() OVERRIDE;
 
   // FileBrowserFunction overrides.
   virtual void GetLocalPathsResponseOnUIThread(const FilePathList& files,
                                                void* context) OVERRIDE;
 
  private:
+#if defined(OS_CHROMEOS)
   struct MountParamaters {
     MountParamaters(const std::string& type,
                     const chromeos::MountPathOptions& options)
         :  mount_type(type), mount_options(options) {}
     ~MountParamaters() {}
     std::string mount_type;
     chromeos::MountPathOptions mount_options;
   };
+#endif
 
   DECLARE_EXTENSION_FUNCTION_NAME("fileBrowserPrivate.addMount");
 };
 
 // Unmounts selected device. Expects mount point path as an argument.
 class RemoveMountFunction
     : public FileBrowserFunction {
  public:
   RemoveMountFunction();
 
@@ skipping 47 matching lines @@
     : public SyncExtensionFunction {
  public:
   GetVolumeMetadataFunction();
 
  protected:
   virtual ~GetVolumeMetadataFunction();
 
   virtual bool RunImpl() OVERRIDE;
 
  private:
-#ifdef OS_CHROMEOS
+#if defined(OS_CHROMEOS)
   const std::string& DeviceTypeToString(chromeos::DeviceType type);
 #endif
 
   DECLARE_EXTENSION_FUNCTION_NAME("fileBrowserPrivate.getVolumeMetadata");
 };
 
 // File Dialog Strings.
 class FileDialogStringsFunction : public SyncExtensionFunction {
  public:
   FileDialogStringsFunction() {}
 
  protected:
   virtual ~FileDialogStringsFunction() {}
 
   // SyncExtensionFunction overrides.
   virtual bool RunImpl() OVERRIDE;
 
  private:
   DECLARE_EXTENSION_FUNCTION_NAME("fileBrowserPrivate.getStrings");
 };
 
 #endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_FILE_BROWSER_PRIVATE_API_H_