Update no include guard warning suppression for instant_struct_traits.h

Switch from an explanatory comment to the string
'no-include-guard-because-multiply-included' to stop
the warning every time the file is edited.

Also add NOLINT(build/header_guard) to stop Tricium from flagging the
same problem.


Change-Id: Iccaf808919606c36ff2c770b44e39b6ba6504bae
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1582459Reviewed-by: Mustafa Emre Acer <meacer@chromium.org>
Commit-Queue: Kyle Milka <kmilka@chromium.org>
Cr-Commit-Position: refs/heads/master@{#657349}

chrome/common/instant_struct_traits.h

@@ -2,7 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Multiply-included file, no traditional include guard.
+// NOLINT(build/header_guard)
+// no-include-guard-because-multiply-included
 #include "chrome/common/search/instant_types.h"
 #include "chrome/common/search/ntp_logging_events.h"
 #include "components/favicon_base/favicon_types.h"