Add optional public header checking to GN build

tools/gn/setup.cc

Index: tools/gn/setup.cc
diff --git a/tools/gn/setup.cc b/tools/gn/setup.cc
index 728a8eba38bd2df73ae67a30071838c07d9f8a10..343ad8ab8428957f82b3f7b3042f3191a7715df8 100644
--- a/tools/gn/setup.cc
+++ b/tools/gn/setup.cc
@@ -18,6 +18,7 @@
 #include "base/strings/utf_string_conversions.h"
 #include "build/build_config.h"
 #include "tools/gn/filesystem_utils.h"
+#include "tools/gn/header_checker.h"
 #include "tools/gn/input_file.h"
 #include "tools/gn/parse_tree.h"
 #include "tools/gn/parser.h"
@@ -123,7 +124,8 @@ CommonSetup::CommonSetup()
       loader_(new LoaderImpl(&build_settings_)),
       builder_(new Builder(loader_.get())),
       check_for_bad_items_(true),
-      check_for_unused_overrides_(true) {
+      check_for_unused_overrides_(true),
+      check_public_headers_(false) {
   loader_->set_complete_callback(base::Bind(&DecrementWorkCount));
 }
 
@@ -165,6 +167,22 @@ bool CommonSetup::RunPostMessageLoop() {
     }
   }
 
+  if (check_public_headers_) {
+    std::vector<const Target*> targets = builder_->GetAllResolvedTargets();
+    scoped_refptr<HeaderChecker> header_checker(
+        new HeaderChecker(&build_settings_, targets));
+
+    std::vector<Err> header_errors;
+    header_checker->Run(&header_errors);
+    for (size_t i = 0; i < header_errors.size(); i++) {
+      if (i > 0)
+        OutputString("___________________\n", DECORATION_YELLOW);
+      header_errors[i].PrintToStdout();
+    }
+    if (!header_errors.empty())
+      return false;
+  }
+
   // Write out tracing and timing if requested.
   const CommandLine* cmdline = CommandLine::ForCurrentProcess();
   if (cmdline->HasSwitch(kTimeSwitch))