Add support for Mac/iOS application bundles to GN tool.

tools/gn/ninja_copy_target_writer.cc

Index: tools/gn/ninja_copy_target_writer.cc
diff --git a/tools/gn/ninja_copy_target_writer.cc b/tools/gn/ninja_copy_target_writer.cc
index b0313bec3f279dc55bc02a7cbaf1f629d2fa57b4..9161a6d1179c55cae5b568064fcc039c19fb2a96 100644
--- a/tools/gn/ninja_copy_target_writer.cc
+++ b/tools/gn/ninja_copy_target_writer.cc
@@ -15,15 +15,16 @@
 #include "tools/gn/toolchain.h"
 
 NinjaCopyTargetWriter::NinjaCopyTargetWriter(const Target* target,
-                                             std::ostream& out)
-    : NinjaTargetWriter(target, out) {
+                                             std::ostream& out,
+                                             Toolchain::ToolType tool_type)
+    : NinjaTargetWriter(target, out), tool_type_(tool_type) {
 }
 
 NinjaCopyTargetWriter::~NinjaCopyTargetWriter() {
 }
 
 void NinjaCopyTargetWriter::Run() {
-  const Tool* copy_tool = target_->toolchain()->GetTool(Toolchain::TYPE_COPY);
+  const Tool* copy_tool = target_->toolchain()->GetTool(tool_type_);
   if (!copy_tool) {
     g_scheduler->FailWithError(Err(
         nullptr, "Copy tool not defined",
@@ -69,7 +70,7 @@ void NinjaCopyTargetWriter::WriteCopyRules(
 
   std::string tool_name =
       GetNinjaRulePrefixForToolchain(settings_) +
-      Toolchain::ToolTypeToName(Toolchain::TYPE_COPY);
+      Toolchain::ToolTypeToName(tool_type_);
 
   OutputFile input_dep =
       WriteInputDepsStampAndGetDep(std::vector<const Target*>());