Add support for command line switches to Features, and as proof that it works,

extensions/common/features/feature.cc

Index: extensions/common/features/feature.cc
diff --git a/extensions/common/features/feature.cc b/extensions/common/features/feature.cc
index e06a44a8727b122aca2f15f01f10c1b84df56759..48d384a310c0911bf64c47a403941f692008a899 100644
--- a/extensions/common/features/feature.cc
+++ b/extensions/common/features/feature.cc
@@ -11,6 +11,7 @@
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
 #include "extensions/common/extension.h"
+#include "extensions/common/manifest.h"
 
 namespace extensions {
 
@@ -43,6 +44,13 @@ Feature::Availability Feature::IsAvailableToExtension(
                                extension->manifest_version());
 }
 
+Feature::Availability Feature::IsAvailableToEnvironment() const {
+  return IsAvailableToManifest("",  // extension_id
+                               Manifest::TYPE_UNKNOWN,
+                               Manifest::INVALID_LOCATION,
+                               -1);  // manifest_version
+}
+
 Feature::Feature() : no_parent_(false) {}
 
 Feature::~Feature() {}