Add get_target_outputs function to GN

tools/gn/scope.cc

Index: tools/gn/scope.cc
diff --git a/tools/gn/scope.cc b/tools/gn/scope.cc
index 931574935e22d36001aebc68931c64b08bc41947..437b31fafde23b0e6aeb07fb9b64a7657e4c7198 100644
--- a/tools/gn/scope.cc
+++ b/tools/gn/scope.cc
@@ -22,21 +22,24 @@ Scope::Scope(const Settings* settings)
     : const_containing_(NULL),
       mutable_containing_(NULL),
       settings_(settings),
-      mode_flags_(0) {
+      mode_flags_(0),
+      item_collector_(NULL) {
 }
 
 Scope::Scope(Scope* parent)
     : const_containing_(NULL),
       mutable_containing_(parent),
       settings_(parent->settings()),
-      mode_flags_(0) {
+      mode_flags_(0),
+      item_collector_(NULL) {
 }
 
 Scope::Scope(const Scope* parent)
     : const_containing_(parent),
       mutable_containing_(NULL),
       settings_(parent->settings()),
-      mode_flags_(0) {
+      mode_flags_(0),
+      item_collector_(NULL) {
 }
 
 Scope::~Scope() {
@@ -390,6 +393,14 @@ const SourceDir& Scope::GetSourceDir() const {
   return source_dir_;
 }
 
+Scope::ItemVector* Scope::GetItemCollector() {
+  if (item_collector_)
+    return item_collector_;
+  if (mutable_containing())
+    return mutable_containing()->GetItemCollector();
+  return NULL;
+}
+
 void Scope::SetProperty(const void* key, void* value) {
   if (!value) {
     DCHECK(properties_.find(key) != properties_.end());