Send the value of google_brand::GetBrand in component update checks.

components/update_client/utils.cc

 // Copyright 2014 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 "components/update_client/utils.h"
 
 #include <stddef.h>
 #include <stdint.h>
+
+#include <algorithm>
 #include <cmath>
 #include <cstring>
 #include <vector>
 
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/files/memory_mapped_file.h"
 #include "base/guid.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_piece.h"
@@ skipping 200 matching lines @@
 
   uint8_t actual_hash[crypto::kSHA256Length] = {0};
   scoped_ptr<crypto::SecureHash> hasher(
       crypto::SecureHash::Create(crypto::SecureHash::SHA256));
   hasher->Update(mmfile.data(), mmfile.length());
   hasher->Finish(actual_hash, sizeof(actual_hash));
 
   return memcmp(actual_hash, &expected_hash[0], sizeof(actual_hash)) == 0;
 }
 
+bool IsValidBrand(const std::string& brand) {
+  const size_t kMaxBrandSize = 4;
+  if (brand.size() > kMaxBrandSize)
+    return false;
+
+  return std::find_if_not(brand.begin(), brand.end(), [](char ch) {
+           return base::IsAsciiAlpha(ch);
+         }) == brand.end();
+}
+
 }  // namespace update_client