Return Windows error code when create-process fails.

chrome/installer/mini_installer/regkey.h

Index: chrome/installer/mini_installer/regkey.h
diff --git a/chrome/installer/mini_installer/regkey.h b/chrome/installer/mini_installer/regkey.h
new file mode 100644
index 0000000000000000000000000000000000000000..288f1a01427868f08e6e5a346e8c4ab1de9c057c
--- /dev/null
+++ b/chrome/installer/mini_installer/regkey.h
@@ -0,0 +1,65 @@
+// 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 CHROME_INSTALLER_MINI_INSTALLER_REGKEY_H_
+#define CHROME_INSTALLER_MINI_INSTALLER_REGKEY_H_
+
+#include <windows.h>
+
+namespace mini_installer {
+
+// A helper class used to manipulate the Windows registry.  Typically, members
+// return Windows last-error codes a la Win32 registry API.
+class RegKey {
+ public:
+  RegKey() : key_(NULL) { }
+  ~RegKey() { Close(); }
+
+  // Opens the key named |sub_key| with given |access| rights.  Returns
+  // ERROR_SUCCESS or some other error.
+  LONG Open(HKEY key, const wchar_t* sub_key, REGSAM access);
+
+  // Returns true if a key is open.
+  bool is_valid() const { return key_ != NULL; }
+
+  // Read a value from the registry into the memory indicated by |value|
+  // (of |value_size| wchar_t units).  Returns ERROR_SUCCESS,
+  // ERROR_FILE_NOT_FOUND, ERROR_MORE_DATA, or some other error.  |value| is
+  // guaranteed to be null-terminated on success.
+  LONG ReadSZValue(const wchar_t* value_name,
+                   wchar_t* value,
+                   size_t value_size) const;
+  LONG ReadDWValue(const wchar_t* value_name, DWORD* value) const;
+
+  // Write a value to the registry.  SZ |value| must be null-terminated.
+  // Returns ERROR_SUCCESS or an error code.
+  LONG WriteSZValue(const wchar_t* value_name, const wchar_t* value);
+  LONG WriteDWValue(const wchar_t* value_name, DWORD value);
+
+  // Closes the key if it was open.
+  void Close();
+
+  // Helper function to read a value from registry.  Returns true if value
+  // is read successfully and stored in parameter value. Returns false
+  // otherwise. |size| is measured in wchar_t units.
+  static bool ReadSZValue(HKEY root_key, const wchar_t *sub_key,
+                          const wchar_t *value_name, wchar_t *value,
+                          size_t value_size);
+
+ private:
+  RegKey(const RegKey&);
+  RegKey& operator=(const RegKey&);
+
+  HKEY key_;
+};  // class RegKey
+
+
+// Helper function to get the RegKey associated with the "client state" of
+// the given |app_guid|.
+bool OpenClientStateKey(HKEY root_key, const wchar_t* app_guid,
+                        REGSAM access, RegKey* key);
+
+}  // namespace mini_installer
+
+#endif  // CHROME_INSTALLER_MINI_INSTALLER_REGKEY_H_