AU: Add a signing test with a private key that doesn't match the public one.

utils.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_UTILS_H__
 #define CHROMEOS_PLATFORM_UPDATE_ENGINE_UTILS_H__
 
 #include <errno.h>
 
 #include <algorithm>
@@ skipping 276 matching lines @@
   ~ScopedExt2fsCloser() { ext2fs_close(filsys_); }
 
  private:
   ext2_filsys filsys_;
   DISALLOW_COPY_AND_ASSIGN(ScopedExt2fsCloser);
 };
 
 // Utility class to delete a file when it goes out of scope.
 class ScopedPathUnlinker {
  public:
-  explicit ScopedPathUnlinker(const std::string& path) : path_(path) {}
+  explicit ScopedPathUnlinker(const std::string& path)
+      : path_(path),
+        should_remove_(true) {}
   ~ScopedPathUnlinker() {
-    if (unlink(path_.c_str()) < 0) {
+    if (should_remove_ && unlink(path_.c_str()) < 0) {
       std::string err_message = strerror(errno);
       LOG(ERROR) << "Unable to unlink path " << path_ << ": " << err_message;
     }
   }
+  void set_should_remove(bool should_remove) { should_remove_ = should_remove; }
+
  private:
   const std::string path_;
+  bool should_remove_;
   DISALLOW_COPY_AND_ASSIGN(ScopedPathUnlinker);
 };
 
 // Utility class to delete an empty directory when it goes out of scope.
 class ScopedDirRemover {
  public:
   explicit ScopedDirRemover(const std::string& path)
       : path_(path),
         should_remove_(true) {}
   ~ScopedDirRemover() {
@@ skipping 99 matching lines @@
     if (_error) {                                                              \
       errno = _error;                                                          \
       LOG(ERROR) << #_x " failed: " << _error;                                 \
       return false;                                                            \
     }                                                                          \
   } while (0)
 
 
 
 #endif  // CHROMEOS_PLATFORM_UPDATE_ENGINE_UTILS_H__