[subresource_filter] Remove some state from the driver factory

components/subresource_filter/core/common/activation_decision.h

Index: components/subresource_filter/core/common/activation_decision.h
diff --git a/components/subresource_filter/core/common/activation_decision.h b/components/subresource_filter/core/common/activation_decision.h
new file mode 100644
index 0000000000000000000000000000000000000000..a39f1e32979197ae18d57f7faa63488a4b4d4d15
--- /dev/null
+++ b/components/subresource_filter/core/common/activation_decision.h
@@ -0,0 +1,38 @@
+// Copyright 2017 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.
+
+#ifndef COMPONENTS_SUBRESOURCE_FILTER_CORE_COMMON_ACTIVATION_DECISION_H_
+#define COMPONENTS_SUBRESOURCE_FILTER_CORE_COMMON_ACTIVATION_DECISION_H_
+
+namespace subresource_filter {
+
+// NOTE: ActivationDecision backs a UMA histogram, so it is append-only.
+enum class ActivationDecision {
+  // The activation decision is unknown, or not known yet.
+  UNKNOWN,
+
+  // Subresource filtering was activated.
+  ACTIVATED,
+
+  // Did not activate because subresource filtering was disabled.
+  ACTIVATION_DISABLED,
+
+  // Did not activate because the main frame document URL had an unsupported
+  // scheme.
+  UNSUPPORTED_SCHEME,
+
+  // Did not activate because the main frame document URL was whitelisted.
+  URL_WHITELISTED,
+
+  // Did not activate because the main frame document URL did not match the
+  // activation list.
+  ACTIVATION_LIST_NOT_MATCHED,
+
+  // Max value for enum.
+  ACTIVATION_DECISION_MAX
+};
+
+}  // namespace subresource_filter
+
+#endif  // COMPONENTS_SUBRESOURCE_FILTER_CORE_COMMON_ACTIVATION_DECISION_H_