Fix filesystem API file_handlers to work for drive on ChromeOS.

webkit/fileapi/isolated_context.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 WEBKIT_FILEAPI_ISOLATED_CONTEXT_H_
 #define WEBKIT_FILEAPI_ISOLATED_CONTEXT_H_
 
 #include <map>
 #include <set>
 #include <string>
@@ skipping 125 matching lines @@
                                  base::FilePath* path) const OVERRIDE;
   virtual bool CrackVirtualPath(const base::FilePath& virtual_path,
                                 std::string* filesystem_id,
                                 FileSystemType* type,
                                 base::FilePath* path) const OVERRIDE;
   virtual FileSystemURL CrackURL(const GURL& url) const OVERRIDE;
   virtual FileSystemURL CreateCrackedFileSystemURL(
       const GURL& origin,
       FileSystemType type,
       const base::FilePath& path) const OVERRIDE;
+  // |GetVirtualPath| is not supported. Always returns false.
+  virtual bool GetVirtualPath(const base::FilePath& full_path,
+                              base::FilePath* virtual_path) const OVERRIDE;
 
   // Returns the virtual root path that looks like /<filesystem_id>.
   base::FilePath CreateVirtualRootPath(const std::string& filesystem_id) const;
 
  private:
   friend struct base::DefaultLazyInstanceTraits<IsolatedContext>;
 
   // Represents each file system instance (defined in the .cc).
   class Instance;
 
@@ skipping 18 matching lines @@
 
   IDToInstance instance_map_;
   PathToID path_to_id_map_;
 
   DISALLOW_COPY_AND_ASSIGN(IsolatedContext);
 };
 
 }  // namespace fileapi
 
 #endif  // WEBKIT_FILEAPI_ISOLATED_CONTEXT_H_