Introduce activation scope logic.

components/subresource_filter/core/common/activation_scope.cc

Index: components/subresource_filter/core/common/activation_scope.cc
diff --git a/components/subresource_filter/core/common/activation_scope.cc b/components/subresource_filter/core/common/activation_scope.cc
new file mode 100644
index 0000000000000000000000000000000000000000..9b939570e99147d01d3e4a9b320af7f080cdecb4
--- /dev/null
+++ b/components/subresource_filter/core/common/activation_scope.cc
@@ -0,0 +1,31 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "components/subresource_filter/core/common/activation_scope.h"
+
+#include <ostream>
+
+#include "base/logging.h"
+
+namespace subresource_filter {
+
+std::ostream& operator<<(std::ostream& os, const ActivationScope& state) {
+  switch (state) {
+    case ActivationScope::NO_SITES:
+      os << "NO_SITES";
+      break;
+    case ActivationScope::ALL_SITES:
+      os << "ALL_SITES";
+      break;
+    case ActivationScope::ACTIVATION_LIST:
+      os << "ACTIVATION_LIST";
+      break;
+    default:
+      NOTREACHED();
+      break;
+  }
+  return os;
+}
+
+}  // namespace subresource_filter