Support more configurability in GN toolchains

tools/gn/command_gen.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 "base/atomicops.h"
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/timer/elapsed_timer.h"
 #include "tools/gn/build_settings.h"
 #include "tools/gn/commands.h"
 #include "tools/gn/ninja_target_writer.h"
 #include "tools/gn/ninja_writer.h"
 #include "tools/gn/scheduler.h"
 #include "tools/gn/setup.h"
 #include "tools/gn/standard_out.h"
+#include "tools/gn/target.h"
 
 namespace commands {
 
 namespace {
 
 // Suppress output on success.
 const char kSwitchQuiet[] = "q";
 
 const char kSwitchCheck[] = "check";
 
 void BackgroundDoWrite(const Target* target,
-                       const Toolchain* toolchain,
                        const std::vector<const Item*>& deps_for_visibility) {
   // Validate visibility.
   Err err;
   for (size_t i = 0; i < deps_for_visibility.size(); i++) {
     if (!Visibility::CheckItemVisibility(target, deps_for_visibility[i],
                                          &err)) {
       g_scheduler->FailWithError(err);
       break;  // Don't return early since we need DecrementWorkCount below.
     }
   }
 
   if (!err.has_error())
-    NinjaTargetWriter::RunAndWriteFile(target, toolchain);
+    NinjaTargetWriter::RunAndWriteFile(target);
   g_scheduler->DecrementWorkCount();
 }
 
 // Called on the main thread.
 void ItemResolvedCallback(base::subtle::Atomic32* write_counter,
                           scoped_refptr<Builder> builder,
                           const BuilderRecord* record) {
   base::subtle::NoBarrier_AtomicIncrement(write_counter, 1);
 
   const Item* item = record->item();
   const Target* target = item->AsTarget();
   if (target) {
-    const Toolchain* toolchain =
-        builder->GetToolchain(target->settings()->toolchain_label());
-    DCHECK(toolchain);
-
     // Collect all dependencies.
     std::vector<const Item*> deps;
     for (BuilderRecord::BuilderRecordSet::const_iterator iter =
              record->all_deps().begin();
          iter != record->all_deps().end();
          ++iter)
       deps.push_back((*iter)->item());
 
     g_scheduler->IncrementWorkCount();
-    g_scheduler->ScheduleWork(
-        base::Bind(&BackgroundDoWrite, target, toolchain, deps));
+    g_scheduler->ScheduleWork(base::Bind(&BackgroundDoWrite, target, deps));
   }
 }
 
 }  // namespace
 
 const char kGen[] = "gen";
 const char kGen_HelpShort[] =
     "gen: Generate ninja files.";
 const char kGen_Help[] =
     "gn gen: Generate ninja files.\n"
@@ skipping 56 matching lines @@
             setup->scheduler().input_file_manager()->GetInputFileCount()) +
         " files in " +
         base::IntToString(elapsed_time.InMilliseconds()) + "ms\n";
     OutputString(stats);
   }
 
   return 0;
 }
 
 }  // namespace commands