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 f69e302f3c2915330634fb10ec6f1e360b364b90..426fd6eb569c8ddd0329a24671a0d5d19d20db08 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.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",
@@ -44,6 +46,7 @@ source_set("unit_tests") {
     "async_document_subresource_filter_unittest.cc",
     "content_ruleset_service_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",
   ]