IWYU: include cmath for using std::sqrt in federated_learning sim hash

Bug: 819294
Change-Id: I4785f465efb51cb7d2c63cc3df5ed86c8e53362d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2248620Reviewed-by: Josh Karlin <jkarlin@chromium.org>
Commit-Queue: José Dapena Paz <jdapena@igalia.com>
Cr-Commit-Position: refs/heads/master@{#779890}

components/federated_learning/sim_hash.cc

@@ -7,6 +7,7 @@
 #include "base/hash/legacy_hash.h"
 
 #include <algorithm>
+#include <cmath>
 
 namespace federated_learning {