Introduce the ThrottleManager

components/subresource_filter/content/browser/BUILD.gn

Index: components/subresource_filter/content/browser/BUILD.gn
diff --git a/components/subresource_filter/content/browser/BUILD.gn b/components/subresource_filter/content/browser/BUILD.gn
index c3c442959e48d1b300c3636491d178395f62400d..2c5e8b05cfe728551acf77bc5bf44b3bb8ae48b8 100644
--- a/components/subresource_filter/content/browser/BUILD.gn
+++ b/components/subresource_filter/content/browser/BUILD.gn
@@ -12,6 +12,8 @@ static_library("browser") {
     "content_ruleset_service_delegate.h",
     "content_subresource_filter_driver_factory.cc",
     "content_subresource_filter_driver_factory.h",
+    "content_subresource_filter_throttle_manager.cc",
+    "content_subresource_filter_throttle_manager.h",
     "subframe_navigation_filtering_throttle.cc",
     "subframe_navigation_filtering_throttle.h",
     "subresource_filter_client.h",
@@ -41,6 +43,7 @@ source_set("unit_tests") {
     "async_document_subresource_filter_unittest.cc",
     "content_ruleset_service_delegate_unittest.cc",
     "content_subresource_filter_driver_factory_unittest.cc",
+    "content_subresource_filter_throttle_manager_unittest.cc",
     "subframe_navigation_filtering_throttle_unittest.cc",
     "verified_ruleset_dealer_unittest.cc",
   ]