Add GCAPI to the GN build.

chrome/installer/gcapi/gcapi.cc

 // Copyright (c) 2012 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.
 
 // NOTE: This code is a legacy utility API for partners to check whether
 //       Chrome can be installed and launched. Recent updates are being made
 //       to add new functionality. These updates use code from Chromium, the old
 //       coded against the win32 api directly. If you have an itch to shave a
 //       yak, feel free to re-write the old code too.
 
@@ skipping 298 matching lines @@
                              &size_returned)) {
     ::CloseHandle(process_token);
     return false;
   }
 
   ::CloseHandle(process_token);
   return (elevation_type == TokenElevationTypeFull);
 }
 
 bool GetUserIdForProcess(size_t pid, wchar_t** user_sid) {
-  HANDLE process_handle = ::OpenProcess(PROCESS_QUERY_INFORMATION, TRUE, pid);
+  HANDLE process_handle =
+      ::OpenProcess(PROCESS_QUERY_INFORMATION, TRUE, static_cast<DWORD>(pid));
   if (process_handle == NULL)
     return false;
 
   HANDLE process_token;
   bool result = false;
   if (::OpenProcessToken(process_handle, TOKEN_QUERY, &process_token)) {
     DWORD size = 0;
     ::GetTokenInformation(process_token, TokenUser, NULL, 0, &size);
     if (::GetLastError() == ERROR_INSUFFICIENT_BUFFER ||
         ::GetLastError() == ERROR_SUCCESS) {
@@ skipping 455 matching lines @@
       key.WriteValue(kRelaunchAllowedAfterValue,
                      FormatDateOffsetByMonths(6)) != ERROR_SUCCESS ||
       !SetRelaunchExperimentLabels(relaunch_brandcode, shell_mode)) {
     if (error_code)
       *error_code = RELAUNCH_ERROR_RELAUNCH_FAILED;
     return FALSE;
   }
 
   return TRUE;
 }