Fixes header issues found by cpp.py

While testing "git cl presubmit --all" I found three latent include
ordering issues in components/sync. All other .cc files in the
components/sync directory pass the presubmits.

Bug: 1309977
Change-Id: I579786e6bb798f0e5a57c73409f5abf0d9708d96
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3561095
Auto-Submit: Bruce Dawson <brucedawson@chromium.org>
Reviewed-by: Victor Vianna <victorvianna@google.com>
Commit-Queue: Victor Vianna <victorvianna@google.com>
Cr-Commit-Position: refs/heads/main@{#987384}

components/sync/base/data_type_histogram.cc

@@ -4,6 +4,8 @@
 
 #include "components/sync/base/data_type_histogram.h"
 
+#include <string>
+
 #include "base/metrics/histogram_functions.h"
 
 namespace syncer {

components/sync/test/model/model_type_store_test_util.cc

@@ -3,12 +3,12 @@
 // found in the LICENSE file.
 
 #include "components/sync/test/model/model_type_store_test_util.h"
-#include "base/memory/raw_ptr.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/debug/leak_annotations.h"
+#include "base/memory/raw_ptr.h"
 #include "base/memory/scoped_refptr.h"
 #include "base/threading/sequenced_task_runner_handle.h"
 #include "components/sync/base/model_type.h"

components/sync/trusted_vault/securebox_unittest.cc

@@ -7,6 +7,7 @@
 #include <cstdint>
 #include <map>
 #include <memory>
+#include <string>
 #include <vector>
 
 #include "base/strings/string_number_conversions.h"