Include implicit_cast.h at all users of it.

util/file/string_file_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,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
 #include "util/file/string_file.h"
 
 #include <string.h>
 
 #include <algorithm>
 #include <limits>
 
 #include "gtest/gtest.h"
+#include "util/misc/implicit_cast.h"
 
 namespace crashpad {
 namespace test {
 namespace {
 
 TEST(StringFile, EmptyFile) {
   StringFile string_file;
   EXPECT_TRUE(string_file.string().empty());
   EXPECT_EQ(0, string_file.Seek(0, SEEK_CUR));
   EXPECT_TRUE(string_file.Write("", 0));
@@ skipping 455 matching lines @@
   EXPECT_EQ(10, string_file.Seek(0, SEEK_CUR));
   EXPECT_FALSE(string_file.SeekSet(std::numeric_limits<ssize_t>::min()));
   EXPECT_EQ(10, string_file.Seek(0, SEEK_CUR));
   EXPECT_FALSE(string_file.SeekSet(std::numeric_limits<FileOffset>::min()));
   EXPECT_EQ(10, string_file.Seek(0, SEEK_CUR));
 }
 
 }  // namespace
 }  // namespace test
 }  // namespace crashpad