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

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

-using System;
-
-namespace Google.Protobuf.Reflection
-{
-    /// <summary>
-    /// Extra information provided by generated code when initializing a message or file descriptor.
-    /// These are constructed as required, and are not long-lived. Hand-written code should
-    /// never need to use this type.
-    /// </summary>
-    public sealed class GeneratedCodeInfo
-    {
-        private static readonly string[] EmptyNames = new string[0];
-        private static readonly GeneratedCodeInfo[] EmptyCodeInfo = new GeneratedCodeInfo[0];
-
-        /// <summary>
-        /// Irrelevant for file descriptors; the CLR type for the message for message descriptors.
-        /// </summary>
-        public Type ClrType { get; private set; }
-
-        /// <summary>
-        /// Irrelevant for file descriptors; the CLR property names (in message descriptor field order)
-        /// for fields in the message for message descriptors.
-        /// </summary>
-        public string[] PropertyNames { get; private set; }
-
-        /// <summary>
-        /// Irrelevant for file descriptors; the CLR property "base" names (in message descriptor oneof order)
-        /// for oneofs in the message for message descriptors. It is expected that for a oneof name of "Foo",
-        /// there will be a "FooCase" property and a "ClearFoo" method.
-        /// </summary>
-        public string[] OneofNames { get; private set; }
-
-        /// <summary>
-        /// The reflection information for types within this file/message descriptor. Elements may be null
-        /// if there is no corresponding generated type, e.g. for map entry types.
-        /// </summary>
-        public GeneratedCodeInfo[] NestedTypes { get; private set; }
-
-        /// <summary>
-        /// The CLR types for enums within this file/message descriptor.
-        /// </summary>
-        public Type[] NestedEnums { get; private set; }
-
-        /// <summary>
-        /// Creates a GeneratedCodeInfo for a message descriptor, with nested types, nested enums, the CLR type, property names and oneof names.
-        /// Each array parameter may be null, to indicate a lack of values.
-        /// The parameter order is designed to make it feasible to format the generated code readably.
-        /// </summary>
-        public GeneratedCodeInfo(Type clrType, string[] propertyNames, string[] oneofNames, Type[] nestedEnums, GeneratedCodeInfo[] nestedTypes)
-        {
-            NestedTypes = nestedTypes ?? EmptyCodeInfo;
-            NestedEnums = nestedEnums ?? ReflectionUtil.EmptyTypes;
-            ClrType = clrType;
-            PropertyNames = propertyNames ?? EmptyNames;
-            OneofNames = oneofNames ?? EmptyNames;
-        }
-
-        /// <summary>
-        /// Creates a GeneratedCodeInfo for a file descriptor, with only types and enums.
-        /// </summary>
-        public GeneratedCodeInfo(Type[] nestedEnums, GeneratedCodeInfo[] nestedTypes)
-            : this(null, null, null, nestedEnums, nestedTypes)
-        {
-        }
-    }
-}