Introduce the ThrottleManager

components/subresource_filter/content/browser/async_document_subresource_filter.h

Index: components/subresource_filter/content/browser/async_document_subresource_filter.h
diff --git a/components/subresource_filter/content/browser/async_document_subresource_filter.h b/components/subresource_filter/content/browser/async_document_subresource_filter.h
index 3d4c9dd3f33ed745269e7be226707cc94ea2b57a..ae7a2b55d10b149cee1d1071825e4b7c608a69d5 100644
--- a/components/subresource_filter/content/browser/async_document_subresource_filter.h
+++ b/components/subresource_filter/content/browser/async_document_subresource_filter.h
@@ -104,14 +104,27 @@ class AsyncDocumentSubresourceFilter {
   // |task_runner|.
   void ReportDisallowedLoad();
 
+  // Must be called after activation state computation is finished.
+  const ActivationState& activation_state() const {
+    return activation_state_.value();
+  }
+
  private:
+  void OnActivateStateCalculated(
+      base::Callback<void(ActivationState)> activation_state_callback,
+      ActivationState activation_state);
+
   // Note: Raw pointer, |core_| already holds a reference to |task_runner_|.
   base::SequencedTaskRunner* task_runner_;
   std::unique_ptr<Core, base::OnTaskRunnerDeleter> core_;
   base::OnceClosure first_disallowed_load_callback_;
 
+  base::Optional<ActivationState> activation_state_;
+
   base::ThreadChecker thread_checker_;
 
+  base::WeakPtrFactory<AsyncDocumentSubresourceFilter> weak_ptr_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(AsyncDocumentSubresourceFilter);
 };