AU: Delta Performer: properly detect idempotent operations

delta_performer.h

 // Copyright (c) 2010 The Chromium OS 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_PERFORMER_H__
 #define CHROMEOS_PLATFORM_UPDATE_ENGINE_DELTA_PERFORMER_H__
 
 #include <inttypes.h>
 
 #include <vector>
 
 #include <google/protobuf/repeated_field.h>
+#include <gtest/gtest_prod.h>  // for FRIEND_TEST
 
 #include "update_engine/file_writer.h"
 #include "update_engine/omaha_hash_calculator.h"
 #include "update_engine/update_metadata.pb.h"
 
 namespace chromeos_update_engine {
 
 class PrefsInterface;
 
 // This class performs the actions in a delta update synchronously. The delta
@@ skipping 57 matching lines @@
   // Returns true if a previous update attempt can be continued based on the
   // persistent preferences and the new update check response hash.
   static bool CanResumeUpdate(PrefsInterface* prefs,
                               std::string update_check_response_hash);
 
   // Resets the persistent update progress state to indicate that an update
   // can't be resumed. Returns true on success, false otherwise.
   static bool ResetUpdateProgress(PrefsInterface* prefs);
 
  private:
+  friend class DeltaPerformerTest;
+  FRIEND_TEST(DeltaPerformerTest, IsIdempotentOperationTest);
+
+  static bool IsIdempotentOperation(
+      const DeltaArchiveManifest_InstallOperation& op);
+
   // Returns true if enough of the delta file has been passed via Write()
   // to be able to perform a given install operation.
   bool CanPerformInstallOperation(
       const DeltaArchiveManifest_InstallOperation& operation);
 
   // Returns true on success.
   bool PerformInstallOperation(
       const DeltaArchiveManifest_InstallOperation& operation);
 
   // These perform a specific type of operation and return true on success.
@@ skipping 61 matching lines @@
 
   // Signatures message blob extracted directly from the payload.
   std::vector<char> signatures_message_data_;
 
   DISALLOW_COPY_AND_ASSIGN(DeltaPerformer);
 };
 
 }  // namespace chromeos_update_engine
 
 #endif  // CHROMEOS_PLATFORM_UPDATE_ENGINE_DELTA_PERFORMER_H__