[subresource_filter] Add TRACE_EVENT probes for frame activation

components/subresource_filter/core/common/activation_state.h

Index: components/subresource_filter/core/common/activation_state.h
diff --git a/components/subresource_filter/core/common/activation_state.h b/components/subresource_filter/core/common/activation_state.h
index 465e6ae25d04b95cb0152e017cad812c972eac6c..772745ecc12fdf59460fdf813b514d01799c0fdd 100644
--- a/components/subresource_filter/core/common/activation_state.h
+++ b/components/subresource_filter/core/common/activation_state.h
@@ -5,8 +5,16 @@
 #ifndef COMPONENTS_SUBRESOURCE_FILTER_CORE_COMMON_ACTIVATION_STATE_H_
 #define COMPONENTS_SUBRESOURCE_FILTER_CORE_COMMON_ACTIVATION_STATE_H_
 
+#include <memory>
+
 #include "components/subresource_filter/core/common/activation_level.h"
 
+namespace base {
+namespace trace_event {
+class TracedValue;
+}  // namespace trace_event
+}  // namespace base
+
 namespace subresource_filter {
 
 // Encompasses all details of whether/how subresource filtering should be
@@ -29,6 +37,8 @@ struct ActivationState {
 
   bool operator!=(const ActivationState& rhs) const { return !operator==(rhs); }
 
+  std::unique_ptr<base::trace_event::TracedValue> ToTracedValue() const;
+
   // The degree to which subresource filtering is activated for the page load.
   ActivationLevel activation_level = ActivationLevel::DISABLED;