Add optional public header checking to GN build

tools/gn/target_generator.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/target_generator.h"
 
 #include "tools/gn/action_target_generator.h"
 #include "tools/gn/binary_target_generator.h"
 #include "tools/gn/build_settings.h"
 #include "tools/gn/config.h"
@@ skipping 119 matching lines @@
   if (!value)
     return;
 
   Target::FileList dest_sources;
   if (!ExtractListOfRelativeFiles(scope_->settings()->build_settings(), *value,
                                   scope_->GetSourceDir(), &dest_sources, err_))
     return;
   target_->sources().swap(dest_sources);
 }
 
+void TargetGenerator::FillPublic() {
+  const Value* value = scope_->GetValue(variables::kPublic, true);
+  if (!value)
+    return;
+
+  // If the public headers are defined, don't default to public.
+  target_->set_all_headers_public(false);
+
+  Target::FileList dest_public;
+  if (!ExtractListOfRelativeFiles(scope_->settings()->build_settings(), *value,
+                                  scope_->GetSourceDir(), &dest_public, err_))
+    return;
+  target_->public_headers().swap(dest_public);
+}
+
 void TargetGenerator::FillSourcePrereqs() {
   const Value* value = scope_->GetValue(variables::kSourcePrereqs, true);
   if (!value)
     return;
 
   Target::FileList dest_reqs;
   if (!ExtractListOfRelativeFiles(scope_->settings()->build_settings(), *value,
                                   scope_->GetSourceDir(), &dest_reqs, err_))
     return;
   target_->source_prereqs().swap(dest_reqs);
@@ skipping 89 matching lines @@
 
 void TargetGenerator::FillForwardDependentConfigs() {
   const Value* value = scope_->GetValue(
       variables::kForwardDependentConfigsFrom, true);
   if (value) {
     ExtractListOfLabels(*value, scope_->GetSourceDir(),
                         ToolchainLabelForScope(scope_),
                         &target_->forward_dependent_configs(), err_);
   }
 }