Reduce the number of worker threads GN uses.

tools/gn/trace.cc

 // Copyright (c) 2013 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 "tools/gn/trace.h"
 
 #include <algorithm>
 #include <map>
 #include <sstream>
 #include <vector>
@@ skipping 184 matching lines @@
       case TraceItem::TRACE_CHECK_HEADERS:
         check_headers.push_back(event);
         break;
       case TraceItem::TRACE_CHECK_HEADER:
         headers_checked++;
         break;
       case TraceItem::TRACE_SETUP:
       case TraceItem::TRACE_FILE_LOAD:
       case TraceItem::TRACE_FILE_WRITE:
       case TraceItem::TRACE_DEFINE_TARGET:
+      case TraceItem::TRACE_ON_RESOLVED:
         break;  // Ignore these for the summary.
     }
   }
 
   std::ostringstream out;
   SummarizeParses(parses, out);
   out << std::endl;
   SummarizeFileExecs(file_execs, out);
   out << std::endl;
   SummarizeScriptExecs(script_execs, out);
@@ skipping 59 matching lines @@
         break;
       case TraceItem::TRACE_FILE_WRITE:
         out << "\"file_write\"";
         break;
       case TraceItem::TRACE_SCRIPT_EXECUTE:
         out << "\"script_exec\"";
         break;
       case TraceItem::TRACE_DEFINE_TARGET:
         out << "\"define\"";
         break;
+      case TraceItem::TRACE_ON_RESOLVED:
+        out << "\"onresolved\"";
+        break;
       case TraceItem::TRACE_CHECK_HEADER:
         out << "\"hdr\"";
         break;
       case TraceItem::TRACE_CHECK_HEADERS:
         out << "\"header_check\"";
         break;
     }
 
     if (!item.toolchain().empty() || !item.cmdline().empty()) {
       out << ",\"args\":{";
@@ skipping 16 matching lines @@
     }
     out << "}";
   }
 
   out << "]}";
 
   std::string out_str = out.str();
   base::WriteFile(file_name, out_str.data(),
                        static_cast<int>(out_str.size()));
 }