Redo GN "args" command

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 149 matching lines @@
   if (!done_) {
     done_ = true;
     if (trace_log) {
       item_->set_end(base::TimeTicks::HighResNow());
       AddTrace(item_);
     }
   }
 }
 
 void EnableTracing() {
-  CHECK(!trace_log);
-  trace_log = new TraceLog;
+  if (!trace_log)
+    trace_log = new TraceLog;
 }
 
 void AddTrace(TraceItem* item) {
   trace_log->Add(item);
 }
 
 std::string SummarizeTraces() {
   if (!trace_log)
     return std::string();
 
@@ skipping 15 matching lines @@
         break;
       case TraceItem::TRACE_SCRIPT_EXECUTE:
         script_execs.push_back(events[i]);
         break;
       case TraceItem::TRACE_CHECK_HEADERS:
         check_headers.push_back(events[i]);
         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:
         break;  // Ignore these for the summary.
     }
   }
 
   std::ostringstream out;
   SummarizeParses(parses, out);
   out << std::endl;
@@ skipping 41 matching lines @@
     out << ",\"ts\":" << item.begin().ToInternalValue();
     out << ",\"ph\":\"X\"";  // "X" = complete event with begin & duration.
     out << ",\"dur\":" << item.delta().InMicroseconds();
 
     quote_buffer.resize(0);
     base::EscapeJSONString(item.name(), true, &quote_buffer);
     out << ",\"name\":" << quote_buffer;
 
     out << ",\"cat\":";
     switch (item.type()) {
+      case TraceItem::TRACE_SETUP:
+        out << "\"setup\"";
+        break;
       case TraceItem::TRACE_FILE_LOAD:
         out << "\"load\"";
         break;
       case TraceItem::TRACE_FILE_PARSE:
         out << "\"parse\"";
         break;
       case TraceItem::TRACE_FILE_EXECUTE:
         out << "\"file_exec\"";
         break;
       case TraceItem::TRACE_FILE_WRITE:
@@ skipping 34 matching lines @@
     }
     out << "}";
   }
 
   out << "]}";
 
   std::string out_str = out.str();
   base::WriteFile(file_name, out_str.data(),
                        static_cast<int>(out_str.size()));
 }