Update //third_party/protobuf to version 3.

third_party/protobuf/csharp/src/Google.Protobuf/Preconditions.cs

Index: third_party/protobuf/csharp/src/Google.Protobuf/Preconditions.cs
diff --git a/third_party/protobuf/src/google/protobuf/io/coded_stream_inl.h b/third_party/protobuf/csharp/src/Google.Protobuf/Preconditions.cs
similarity index 51%
copy from third_party/protobuf/src/google/protobuf/io/coded_stream_inl.h
copy to third_party/protobuf/csharp/src/Google.Protobuf/Preconditions.cs
index 144f44f0635304bd7acc72ae628eab2d0a1998d3..2db35ff63a730e9a70f3dcd91f98d0d195b61ea2 100644
--- a/third_party/protobuf/src/google/protobuf/io/coded_stream_inl.h
+++ b/third_party/protobuf/csharp/src/Google.Protobuf/Preconditions.cs
@@ -1,6 +1,7 @@
+#region Copyright notice and license
 // Protocol Buffers - Google's data interchange format
 // Copyright 2008 Google Inc.  All rights reserved.
-// http://code.google.com/p/protobuf/
+// 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
@@ -27,42 +28,47 @@
 // 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
 
-// Author: jasonh@google.com (Jason Hsueh)
-//
-// Implements methods of coded_stream.h that need to be inlined for performance
-// reasons, but should not be defined in a public header.
-
-#ifndef GOOGLE_PROTOBUF_IO_CODED_STREAM_INL_H__
-#define GOOGLE_PROTOBUF_IO_CODED_STREAM_INL_H__
-
-#include <google/protobuf/io/coded_stream.h>
-#include <string>
-#include <google/protobuf/stubs/stl_util.h>
+using System;
 
-namespace google {
-namespace protobuf {
-namespace io {
+namespace Google.Protobuf
+{
+    /// <summary>
+    /// Helper methods for throwing exceptions
+    /// </summary>
+    public static class Preconditions
+    {
+        /// <summary>
+        /// Throws an ArgumentNullException if the given value is null, otherwise
+        /// return the value to the caller.
+        /// </summary>
+        public static T CheckNotNull<T>(T value, string name) where T : class
+        {
+            if (value == null)
+            {
+                throw new ArgumentNullException(name);
+            }
+            return value;
+        }
 
-inline bool CodedInputStream::InternalReadStringInline(string* buffer,
-                                                       int size) {
-  if (size < 0) return false;  // security: size is often user-supplied
-
-  if (BufferSize() >= size) {
-    STLStringResizeUninitialized(buffer, size);
-    // When buffer is empty, string_as_array(buffer) will return NULL but memcpy
-    // requires non-NULL pointers even when size is 0. Hench this check.
-    if (size > 0) {
-      memcpy(string_as_array(buffer), buffer_, size);
-      Advance(size);
+        /// <summary>
+        /// Throws an ArgumentNullException if the given value is null, otherwise
+        /// return the value to the caller.
+        /// </summary>
+        /// <remarks>
+        /// This is equivalent to <see cref="CheckNotNull{T}(T, string)"/> but without the type parameter
+        /// constraint. In most cases, the constraint is useful to prevent you from calling CheckNotNull
+        /// with a value type - but it gets in the way if either you want to use it with a nullable
+        /// value type, or you want to use it with an unconstrained type parameter.
+        /// </remarks>
+        internal static T CheckNotNullUnconstrained<T>(T value, string name)
+        {
+            if (value == null)
+            {
+                throw new ArgumentNullException(name);
+            }
+            return value;
+        }
     }
-    return true;
-  }
-
-  return ReadStringFallback(buffer, size);
-}
-
-}  // namespace io
-}  // namespace protobuf
-}  // namespace google
-#endif  // GOOGLE_PROTOBUF_IO_CODED_STREAM_INL_H__
+}