Add optional public header checking to GN build

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"
 
 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.
@@ skipping 61 matching lines @@
         "I expected something more like \"gn gen out/foo\"\n"
         "You can also see \"gn help gen\".").PrintToStdout();
     return 1;
   }
 
   // Deliberately leaked to avoid expensive process teardown.
   Setup* setup = new Setup();
   if (!setup->DoSetup(args[0]))
     return 1;
 
+  if (CommandLine::ForCurrentProcess()->HasSwitch(kSwitchCheck))
+    setup->set_check_public_headers(true);
+
   // Cause the load to also generate the ninja files for each target. We wrap
   // the writing to maintain a counter.
   base::subtle::Atomic32 write_counter = 0;
   setup->builder()->set_resolved_callback(
       base::Bind(&ItemResolvedCallback, &write_counter,
                  scoped_refptr<Builder>(setup->builder())));
 
   // Do the actual load. This will also write out the target ninja files.
   if (!setup->Run())
     return 1;
@@ skipping 15 matching lines @@
             setup->scheduler().input_file_manager()->GetInputFileCount()) +
         " files in " +
         base::IntToString(elapsed_time.InMilliseconds()) + "ms\n";
     OutputString(stats);
   }
 
   return 0;
 }
 
 }  // namespace commands