Swap from base/stl_util.h to cxx17_backports.h in net/ .cc files.

base::size() has been moved to base/cxx17_backports.h, so .cc files that
use base::size(), but no other function from base/stl_util.h, can
directly include base/cxx17_backports.h and not base/stl_util.h.

Bug: 1210983
Change-Id: I946c640c8a76c54a3b817e89e8f8591732d796da
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2914197
Reviewed-by: Eric Orth <[email protected]>
Commit-Queue: Lei Zhang <[email protected]>
Cr-Commit-Position: refs/heads/master@{#889449}
diff --git a/net/socket/client_socket_pool_base_unittest.cc b/net/socket/client_socket_pool_base_unittest.cc
index 80d48686..929de6a 100644
--- a/net/socket/client_socket_pool_base_unittest.cc
+++ b/net/socket/client_socket_pool_base_unittest.cc
@@ -12,13 +12,13 @@
 #include "base/callback.h"
 #include "base/callback_helpers.h"
 #include "base/check_op.h"
+#include "base/cxx17_backports.h"
 #include "base/location.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "base/notreached.h"
 #include "base/run_loop.h"
 #include "base/single_thread_task_runner.h"
-#include "base/stl_util.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/stringprintf.h"
 #include "base/test/scoped_feature_list.h"