AU: delta compress the kernel partition

src/platform/update_engine/delta_diff_generator.h

 // Copyright (c) 2010 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 CHROMEOS_PLATFORM_UPDATE_ENGINE_DELTA_DIFF_GENERATOR_H__
 #define CHROMEOS_PLATFORM_UPDATE_ENGINE_DELTA_DIFF_GENERATOR_H__
 
 #include <string>
 #include <vector>
 #include "base/basictypes.h"
@@ skipping 22 matching lines @@
     // Generally, there will be a vector of Block objects whose length
     // is the number of blocks on the install partition.
     Block() : reader(Vertex::kInvalidIndex), writer(Vertex::kInvalidIndex) {}
     Vertex::Index reader;
     Vertex::Index writer;
   };
 
   // This is the only function that external users of the class should call.
   // old_image and new_image are paths to two image files. They should be
   // mounted read-only at paths old_root and new_root respectively.
+  // {old,new}_kernel_part are paths to the old and new kernel partition
+  // images, respectively.
   // output_path is the filename where the delta update should be written.
   // Returns true on success.
   static bool GenerateDeltaUpdateFile(const std::string& old_root,
                                       const std::string& old_image,
                                       const std::string& new_root,
                                       const std::string& new_image,
+                                      const std::string& old_kernel_part,
+                                      const std::string& new_kernel_part,
                                       const std::string& output_path);
 
   // These functions are public so that the unit tests can access them:
 
   // Reads old_filename (if it exists) and a new_filename and determines
   // the smallest way to encode this file for the diff. It stores
   // necessary data in out_data and fills in out_op.
   // If there's no change in old and new files, it creates a MOVE
   // operation. If there is a change, or the old file doesn't exist,
   // the smallest of REPLACE, REPLACE_BZ, or BSDIFF wins.
@@ skipping 52 matching lines @@
   DISALLOW_IMPLICIT_CONSTRUCTORS(DeltaDiffGenerator);
 };
 
 extern const char* const kBsdiffPath;
 extern const char* const kBspatchPath;
 extern const char* const kDeltaMagic;
 
 };  // namespace chromeos_update_engine
 
 #endif  // CHROMEOS_PLATFORM_UPDATE_ENGINE_DELTA_DIFF_GENERATOR_H__