Move download filename determintion into a separate class.

chrome/browser/download/download_prefs.h

 // 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.
 
 #ifndef CHROME_BROWSER_DOWNLOAD_DOWNLOAD_PREFS_H_
 #define CHROME_BROWSER_DOWNLOAD_DOWNLOAD_PREFS_H_
 
 #include <set>
 
 #include "base/files/file_path.h"
@@ skipping 31 matching lines @@
   // to choose another download location).
   bool PromptForDownload() const;
 
   // Returns true if the download path preference is managed.
   bool IsDownloadPathManaged() const;
 
   // Returns true if there is at least one file extension registered
   // for auto-open.
   bool IsAutoOpenUsed() const;
 
-  bool IsAutoOpenEnabledForExtension(
-      const base::FilePath::StringType& extension) const;
+  // Returns true if |path| should be opened automatically based on
+  // |path.Extension()|.
+  bool IsAutoOpenEnabledBasedOnExtension(const base::FilePath& path) const;
 
   // Enables auto-open based on file extension. Returns true on success.
   // TODO(phajdan.jr): Add WARN_UNUSED_RESULT here.
   bool EnableAutoOpenBasedOnExtension(const base::FilePath& file_name);
 
   // Disables auto-open based on file extension.
   void DisableAutoOpenBasedOnExtension(const base::FilePath& file_name);
 
   void ResetAutoOpen();
 
@@ skipping 12 matching lines @@
                     const base::FilePath::StringType& b) const;
   };
   typedef std::set<base::FilePath::StringType,
                    AutoOpenCompareFunctor> AutoOpenSet;
   AutoOpenSet auto_open_;
 
   DISALLOW_COPY_AND_ASSIGN(DownloadPrefs);
 };
 
 #endif  // CHROME_BROWSER_DOWNLOAD_DOWNLOAD_PREFS_H_