Cancel prerendering when a request is paused or removed.

components/offline_pages/background/request_coordinator.h

Index: components/offline_pages/background/request_coordinator.h
diff --git a/components/offline_pages/background/request_coordinator.h b/components/offline_pages/background/request_coordinator.h
index 2b874332bc58508c60d21a306186a16b792aed2c..ef92fbfc2b2e13a1084f74f19eed89a247ae5b8b 100644
--- a/components/offline_pages/background/request_coordinator.h
+++ b/components/offline_pages/background/request_coordinator.h
@@ -183,6 +183,9 @@ class RequestCoordinator : public KeyedService, public RequestNotifier {
 
   void TryNextRequest();
 
+  // If there is an active request in the list, cancel that request.
+  void CancelActiveRequestIfItMatches(const std::vector<int64_t>& request_ids);
+
   // Returns the appropriate offliner to use, getting a new one from the factory
   // if needed.
   void GetOffliner();