win: avoid warning in StringFileWriter.SeekInvalid test

util/file/string_file_writer_test.cc

 // Copyright 2014 The Crashpad Authors. All rights reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
@@ skipping 344 matching lines @@
   EXPECT_TRUE(writer.string().empty());
 
   static_assert(SEEK_SET != 3 && SEEK_CUR != 3 && SEEK_END != 3,
                 "3 must be invalid for whence");
   EXPECT_LT(writer.Seek(0, 3), 0);
 
   writer.Reset();
   EXPECT_EQ(0, writer.Seek(0, SEEK_CUR));
   EXPECT_TRUE(writer.string().empty());
 
-  const off_t kMaxOffset =
+  const off_t kMaxOffset = static_cast<off_t>(
       std::min(implicit_cast<uint64_t>(std::numeric_limits<off_t>::max()),
-               implicit_cast<uint64_t>(std::numeric_limits<size_t>::max()));
+               implicit_cast<uint64_t>(std::numeric_limits<size_t>::max())));
 
   EXPECT_EQ(kMaxOffset, writer.Seek(kMaxOffset, SEEK_SET));
   EXPECT_EQ(kMaxOffset, writer.Seek(0, SEEK_CUR));
   EXPECT_LT(writer.Seek(1, SEEK_CUR), 0);
 
   EXPECT_EQ(1, writer.Seek(1, SEEK_SET));
   EXPECT_EQ(1, writer.Seek(0, SEEK_CUR));
   EXPECT_LT(writer.Seek(kMaxOffset, SEEK_CUR), 0);
 }
 
 }  // namespace
 }  // namespace test
 }  // namespace crashpad