Revert https://codereview.chromium.org/1291903002 (protobuf roll).

third_party/protobuf/csharp/src/Google.Protobuf/Reflection/DescriptorValidationException.cs

-#region Copyright notice and license
-// Protocol Buffers - Google's data interchange format
-// Copyright 2008 Google Inc.  All rights reserved.
-// https://developers.google.com/protocol-buffers/
-//
-// Redistribution and use in source and binary forms, with or without
-// modification, are permitted provided that the following conditions are
-// met:
-//
-//     * Redistributions of source code must retain the above copyright
-// notice, this list of conditions and the following disclaimer.
-//     * Redistributions in binary form must reproduce the above
-// copyright notice, this list of conditions and the following disclaimer
-// in the documentation and/or other materials provided with the
-// distribution.
-//     * Neither the name of Google Inc. nor the names of its
-// contributors may be used to endorse or promote products derived from
-// this software without specific prior written permission.
-//
-// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-#endregion
-
-using System;
-
-namespace Google.Protobuf.Reflection
-{
-    /// <summary>
-    /// Thrown when building descriptors fails because the source DescriptorProtos
-    /// are not valid.
-    /// </summary>
-    public sealed class DescriptorValidationException : Exception
-    {
-        private readonly String name;
-        private readonly string description;
-
-        /// <value>
-        /// The full name of the descriptor where the error occurred.
-        /// </value>
-        public String ProblemSymbolName
-        {
-            get { return name; }
-        }
-
-        /// <value>
-        /// A human-readable description of the error. (The Message property
-        /// is made up of the descriptor's name and this description.)
-        /// </value>
-        public string Description
-        {
-            get { return description; }
-        }
-
-        internal DescriptorValidationException(IDescriptor problemDescriptor, string description) :
-            base(problemDescriptor.FullName + ": " + description)
-        {
-            // Note that problemDescriptor may be partially uninitialized, so we
-            // don't want to expose it directly to the user.  So, we only provide
-            // the name and the original proto.
-            name = problemDescriptor.FullName;
-            this.description = description;
-        }
-
-        internal DescriptorValidationException(IDescriptor problemDescriptor, string description, Exception cause) :
-            base(problemDescriptor.FullName + ": " + description, cause)
-        {
-            name = problemDescriptor.FullName;
-            this.description = description;
-        }
-    }
-}