Include "public" source files in generated Xcode project.

tools/gn/xcode_writer.cc

Index: tools/gn/xcode_writer.cc
diff --git a/tools/gn/xcode_writer.cc b/tools/gn/xcode_writer.cc
index 41af6289bd6010491acc7be3cdb330798b6c0f3e..8b96db49cbbfd25874e7d8e26d53744cdc9c6268 100644
--- a/tools/gn/xcode_writer.cc
+++ b/tools/gn/xcode_writer.cc
@@ -404,7 +404,7 @@ void XcodeWriter::CreateProductsProject(
       new PBXProject("products", config_name, source_path, attributes));
   SourceDir source_dir("//");
 
-  // Add all source files for indexing.
+  // Add all source files for indexing, both private and public.
   std::vector<SourceFile> sources;
   for (const Target* target : all_targets) {
     for (const SourceFile& source : target->sources()) {
@@ -413,6 +413,16 @@ void XcodeWriter::CreateProductsProject(
 
       sources.push_back(source);
     }
+
+    if (target->all_headers_public())
+      continue;
+
+    for (const SourceFile& source : target->public_headers()) {
+      if (IsStringInOutputDir(build_settings->build_dir(), source.value()))
+        continue;
+
+      sources.push_back(source);
+    }
   }
 
   // Sort sources to ensure determinisn of the project file generation and