Update from https://crrev.com/306655

net/quic/congestion_control/cube_root.cc

 // Copyright (c) 2013 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/quic/congestion_control/cube_root.h"
 
 #include "base/logging.h"
 
 namespace {
 
@@ skipping 46 matching lines @@
 namespace net {
 
 // Calculate the cube root using a table lookup followed by one Newton-Raphson
 // iteration.
 uint32 CubeRoot::Root(uint64 a) {
   uint32 msb = FindMostSignificantBit(a);
   DCHECK_LE(msb, 64u);
 
   if (msb < 7) {
     // MSB in our table.
-    return ((cube_root_table[static_cast<uint32>(a)]) + 31) >> 6;
+    return ((cube_root_table[a]) + 31) >> 6;
   }
   // MSB          7,  8,  9, 10, 11, 12, 13, 14, 15, 16, ...
   // cubic_shift  1,  1,  1,  2,  2,  2,  3,  3,  3,  4, ...
   uint32 cubic_shift = (msb - 4);
   cubic_shift = ((cubic_shift * 342) >> 10);  // Div by 3, biased high.
 
   // 4 to 6 bits accuracy depending on MSB.
-  uint32 down_shifted_to_6bit = (a >> (cubic_shift * 3));
-  uint64 root = ((cube_root_table[down_shifted_to_6bit] + 10) << cubic_shift)
-      >> 6;
+  uint64 root =
+      ((cube_root_table[a >> (cubic_shift * 3)] + 10) << cubic_shift) >> 6;
 
   // Make one Newton-Raphson iteration.
   // Since x has an error (inaccuracy due to the use of fix point) we get a
   // more accurate result by doing x * (x - 1) instead of x * x.
   root = 2 * root + (a / (root * (root - 1)));
   root = ((root * 341) >> 10);  // Div by 3, biased low.
   return static_cast<uint32>(root);
 }
 
 }  // namespace net