Update //third_party/protobuf to version 3.

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;
+        }
+    }
+}