Use implicit_cast<> instead of static_cast<> whenever possible

util/net/http_body_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 28 matching lines @@
   EXPECT_EQ(0, stream.GetBytesBuffer(buf, sizeof(buf)));
   ExpectBufferSet(buf, '!', sizeof(buf));
 }
 
 TEST(StringHTTPBodyStream, SmallString) {
   uint8_t buf[32];
   memset(buf, '!', sizeof(buf));
 
   std::string string("Hello, world");
   StringHTTPBodyStream stream(string);
-  EXPECT_EQ(static_cast<ssize_t>(string.length()),
+  EXPECT_EQ(implicit_cast<ssize_t>(string.length()),
             stream.GetBytesBuffer(buf, sizeof(buf)));
 
   std::string actual(reinterpret_cast<const char*>(buf), string.length());
   EXPECT_EQ(string, actual);
   ExpectBufferSet(buf + string.length(), '!', sizeof(buf) - string.length());
 
   EXPECT_EQ(0, stream.GetBytesBuffer(buf, sizeof(buf)));
 }
 
 TEST(StringHTTPBodyStream, MultipleReads) {
@@ skipping 152 matching lines @@
   EXPECT_EQ(expected_string, actual_string);
 }
 
 INSTANTIATE_TEST_CASE_P(VariableBufferSize,
                         CompositeHTTPBodyStreamBufferSize,
                         testing::Values(1, 2, 9, 16, 31, 128));
 
 }  // namespace
 }  // namespace test
 }  // namespace crashpad