Fix C4334 (32-bit shift converted to 64-bit) warnings

net/base/mime_sniffer_perftest.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/base/mime_sniffer.h"
 
 #include <vector>
 
 #include "base/bits.h"
 #include "base/logging.h"
@@ skipping 67 matching lines @@
 }
 
 TEST(MimeSnifferTest, PlainTextPerfTest) {
   // Android systems have a relatively small CPU cache (512KB to 2MB).
   // It is better if the test data fits in cache so that we are not just
   // testing bus bandwidth.
   const size_t kTargetSize = 1 << 18;  // 256KB
   const size_t kWarmupIterations = 16;
   const size_t kMeasuredIterations = 1 << 15;
   std::string plaintext = kRepresentativePlainText;
-  // The purpose of the static_cast<size_t>() here is to prevent MSVC from
-  // complaining about an implicit promotion to 64 bits when compiling 64-bit.
-  size_t expected_size =
-      plaintext.size() *
-      static_cast<size_t>(
-          1u << base::bits::Log2Ceiling(kTargetSize / plaintext.size()));
+  size_t expected_size = plaintext.size() << base::bits::Log2Ceiling(
+                             kTargetSize / plaintext.size());
   plaintext.reserve(expected_size);
   while (plaintext.size() < kTargetSize)
     plaintext += plaintext;
   DCHECK_EQ(expected_size, plaintext.size());
   RunLooksLikeBinary(plaintext, kWarmupIterations);
   base::ElapsedTimer elapsed_timer;
   RunLooksLikeBinary(plaintext, kMeasuredIterations);
   LOG(INFO) << (elapsed_timer.Elapsed().InMicroseconds() * 1000 * 1024 /
                 (static_cast<int64_t>(plaintext.size()) * kMeasuredIterations))
             << "ns per KB";
 }
 
 }  // namespace net
 }  // namespace