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 5e330393b3b945c44de920ead3448e656cf05eb0..f2b708afdc8bda488dc3dc6c9c7eb87924f5d499 100644
--- a/components/subresource_filter/content/browser/BUILD.gn
+++ b/components/subresource_filter/content/browser/BUILD.gn
@@ -14,6 +14,8 @@ static_library("browser") {
     "content_subresource_filter_driver.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",
     "verified_ruleset_dealer.cc",
@@ -45,6 +47,7 @@ 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",
   ]