Implement an API to allow passing an "ap" parameter to component updates.

chrome/browser/component_updater/sth_set_component_installer.cc

 // Copyright 2016 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 "chrome/browser/component_updater/sth_set_component_installer.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/files/file_enumerator.h"
@@ skipping 86 matching lines @@
 }
 
 void STHSetComponentInstallerTraits::GetHash(std::vector<uint8_t>* hash) const {
   hash->assign(std::begin(kPublicKeySHA256), std::end(kPublicKeySHA256));
 }
 
 std::string STHSetComponentInstallerTraits::GetName() const {
   return kSTHSetFetcherManifestName;
 }
 
+std::string STHSetComponentInstallerTraits::GetAp() const {
+  return std::string();
+}
+
 void STHSetComponentInstallerTraits::LoadSTHsFromDisk(
     const base::FilePath& sths_path,
     const base::Version& version) {
   if (sths_path.empty())
     return;
 
   base::FileEnumerator sth_file_enumerator(sths_path, false,
                                            base::FileEnumerator::FILES,
                                            FILE_PATH_LITERAL("*.sth"));
   base::FilePath sth_file_path;
@@ skipping 72 matching lines @@
 
   scoped_ptr<ComponentInstallerTraits> traits(
       new STHSetComponentInstallerTraits(std::move(distributor)));
   // |cus| will take ownership of |installer| during installer->Register(cus).
   DefaultComponentInstaller* installer =
       new DefaultComponentInstaller(std::move(traits));
   installer->Register(cus, base::Closure());
 }
 
 }  // namespace component_updater