GN: don't write separate files for non-binary targets

tools/gn/visual_studio_writer.cc

Index: tools/gn/visual_studio_writer.cc
diff --git a/tools/gn/visual_studio_writer.cc b/tools/gn/visual_studio_writer.cc
index 401782f5217434c4d6965e5211e54c71ea4ed8b9..fb6d923db0a02ec61d669ca8c1d33db62294defc 100644
--- a/tools/gn/visual_studio_writer.cc
+++ b/tools/gn/visual_studio_writer.cc
@@ -166,12 +166,12 @@ base::StringPiece FindParentDir(const std::string* path) {
 }
 
 bool FilterTargets(const BuildSettings* build_settings,
-                   Builder* builder,
+                   const Builder& builder,
                    const std::string& dir_filters,
                    std::vector<const Target*>* targets,
                    Err* err) {
   if (dir_filters.empty()) {
-    *targets = builder->GetAllResolvedTargets();
+    *targets = builder.GetAllResolvedTargets();
     return true;
   }
 
@@ -180,7 +180,7 @@ bool FilterTargets(const BuildSettings* build_settings,
                                           err))
     return false;
 
-  commands::FilterTargetsByPatterns(builder->GetAllResolvedTargets(), filters,
+  commands::FilterTargetsByPatterns(builder.GetAllResolvedTargets(), filters,
                                     targets);
 
   std::set<Label> labels;
@@ -269,7 +269,7 @@ VisualStudioWriter::~VisualStudioWriter() {
 
 // static
 bool VisualStudioWriter::RunAndWriteFiles(const BuildSettings* build_settings,
-                                          Builder* builder,
+                                          const Builder& builder,
                                           Version version,
                                           const std::string& sln_name,
                                           const std::string& dir_filters,