Fixed bug where an empty version string is considered valid.

base/version.h

 // Copyright (c) 2009 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 BASE_VERSION_H_
 #define BASE_VERSION_H_
 
 #include <string>
 #include <vector>
 
 #include "base/basictypes.h"
+#include "testing/gtest/include/gtest/gtest_prod.h"
 
 class Version {
  public:
   // The version string must be made up of 1 or more uint16's separated
   // by '.'. Returns NULL if string is not in this format.
   // Caller is responsible for freeing the Version object once done.
   static Version* GetVersionFromString(const std::wstring& version_str);
   static Version* GetVersionFromString(const std::string& version_str);
 
+  // Exposed only so that a Version can be stored in STL containers;
+  // any call to the methods below on a default-constructed Version
+  // will DCHECK.
+  Version();
+
   ~Version() {}
 
   bool Equals(const Version& other) const;
 
   // Returns -1, 0, 1 for <, ==, >.
   int CompareTo(const Version& other) const;
 
   // Return the string representation of this version.
   const std::string GetString() const;
 
   const std::vector<uint16>& components() const { return components_; }
 
  private:
-  Version() {}
   bool InitFromString(const std::string& version_str);
 
+  bool is_valid_;
   std::vector<uint16> components_;
+
+  FRIEND_TEST(VersionTest, DefaultConstructor);
+  FRIEND_TEST(VersionTest, GetVersionFromString);
+  FRIEND_TEST(VersionTest, Compare);
 };
 
 #endif  // BASE_VERSION_H_