Expose computation of md5 content checksums for files via a file manager private API.

chrome/browser/chromeos/extensions/file_manager/private_api_file_system.h

 // 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.
 //
 // This file provides file system related API functions.
 
 #ifndef CHROME_BROWSER_CHROMEOS_EXTENSIONS_FILE_MANAGER_PRIVATE_API_FILE_SYSTEM_H_
 #define CHROME_BROWSER_CHROMEOS_EXTENSIONS_FILE_MANAGER_PRIVATE_API_FILE_SYSTEM_H_
 
 #include <string>
@@ skipping 211 matching lines @@
   virtual ~FileManagerPrivateInternalResolveIsolatedEntriesFunction() {}
 
   // AsyncExtensionFunction overrides.
   virtual bool RunAsync() override;
 
  private:
   void RunAsyncAfterConvertFileDefinitionListToEntryDefinitionList(scoped_ptr<
       file_manager::util::EntryDefinitionList> entry_definition_list);
 };
 
+class FileManagerPrivateComputeChecksumFunction
+    : public LoggedAsyncExtensionFunction {
+ public:
+  DECLARE_EXTENSION_FUNCTION("fileManagerPrivate.computeChecksum",
+                             FILEMANAGERPRIVATE_COMPUTECHECKSUM)
+
+ protected:
+  virtual ~FileManagerPrivateComputeChecksumFunction() {}
+
+  // AsyncExtensionFunction overrides.
+  virtual bool RunAsync() override;
+
+ private:
+  void Respond(const std::string& hash);
+};
+
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_CHROMEOS_EXTENSIONS_FILE_MANAGER_PRIVATE_API_FILE_SYSTEM_H_