Introduce the ThrottleManager

components/subresource_filter/content/browser/activation_state_computing_navigation_throttle.h

Index: components/subresource_filter/content/browser/activation_state_computing_navigation_throttle.h
diff --git a/components/subresource_filter/content/browser/activation_state_computing_navigation_throttle.h b/components/subresource_filter/content/browser/activation_state_computing_navigation_throttle.h
index 2fc7917078c317e52381175990f1d4f19a0c59f1..c3415734a27c14301431306979da5e724a74ee7a 100644
--- a/components/subresource_filter/content/browser/activation_state_computing_navigation_throttle.h
+++ b/components/subresource_filter/content/browser/activation_state_computing_navigation_throttle.h
@@ -63,22 +63,23 @@ class ActivationStateComputingNavigationThrottle
   // frame.
   std::unique_ptr<AsyncDocumentSubresourceFilter> ReleaseFilter();
 
-  // Gets the activation state calculated for this navigation. Must be called
-  // after the navigation is resumed from getting paused in WillProcessResponse,
-  // which, for example, will have happened at ReadyToCommitNavigation.
-  const ActivationState& GetActivationState() const;
+  AsyncDocumentSubresourceFilter* filter() { return async_filter_.get(); }
+
+  void WillSendActivationToRenderer();
 
  private:
-  void SetActivationStateAndResume(ActivationState state);
+  void OnActivationStateComputed(ActivationState state);
+  void set_filter(
+      std::unique_ptr<AsyncDocumentSubresourceFilter> async_filter) {
+    async_filter_ = std::move(async_filter);
+  }
 
   ActivationStateComputingNavigationThrottle(
       content::NavigationHandle* navigation_handle,
       const base::Optional<ActivationState> parent_activation_state,
       VerifiedRuleset::Handle* ruleset_handle);
 
-  // These members are optional to allow DCHECKing their existence at certain
-  // points in the navigation flow.
-  base::Optional<ActivationState> activation_state_;
+  // Optional to allow for DCHECKing.
   base::Optional<ActivationState> parent_activation_state_;
 
   std::unique_ptr<AsyncDocumentSubresourceFilter> async_filter_;
@@ -87,6 +88,12 @@ class ActivationStateComputingNavigationThrottle
   // nullptr until NotifyPageActivationWithRuleset is called.
   VerifiedRuleset::Handle* ruleset_handle_;
 
+  // Becomes true when the throttle manager reaches ReadyToCommitNavigation and
+  // sends an activation IPC to the render process. Makes sure a caller cannot
+  // take ownership of the subresource filter unless an activation IPC is sent
+  // to the renderer.
+  bool will_send_activation_to_renderer_ = false;
+
   base::WeakPtrFactory<ActivationStateComputingNavigationThrottle>
       weak_ptr_factory_;