Support API aliases

extensions/common/features/complex_feature.cc

Index: extensions/common/features/complex_feature.cc
diff --git a/extensions/common/features/complex_feature.cc b/extensions/common/features/complex_feature.cc
index ed129da1e6413884c70e853bcb3b27c4aa4ed90b..3780b7218f04a0d1c3f96c78955661a1a8a9007c 100644
--- a/extensions/common/features/complex_feature.cc
+++ b/extensions/common/features/complex_feature.cc
@@ -98,6 +98,28 @@ bool ComplexFeature::IsIdInWhitelist(const std::string& extension_id) const {
   return false;
 }
 
+std::string ComplexFeature::GetAlias() const {
+  for (FeatureList::const_iterator it = features_.begin();
+       it != features_.end(); ++it) {
+    std::string alias = (*it)->GetAlias();
+    if (!alias.empty())
+      return alias;
+  }
+
+  return std::string();
+}
+
+std::string ComplexFeature::GetSource() const {
+  for (FeatureList::const_iterator it = features_.begin();
+       it != features_.end(); ++it) {
+    std::string source = (*it)->GetSource();
+    if (!source.empty())
+      return source;
+  }
+
+  return std::string();
+}
+
 bool ComplexFeature::IsInternal() const {
   // Constructor verifies that composed features are consistent, thus we can
   // return just the first feature's value.