Introduce a layering in the invalidation component as public and impl

components/BUILD.gn

Index: components/BUILD.gn
diff --git a/components/BUILD.gn b/components/BUILD.gn
index 0d41d048de6c0ca450759b6d189243a103918cdf..72d53f62699e976edc49c0bdf446175cf4d17dd2 100644
--- a/components/BUILD.gn
+++ b/components/BUILD.gn
@@ -55,7 +55,7 @@ group("all_components") {
     "//components/history/core/common",
     "//components/history/core/test",
     "//components/infobars/core",
-    "//components/invalidation",
+    "//components/invalidation/impl",
     "//components/json_schema",
     "//components/keyed_service/content",
     "//components/language_usage_metrics",
@@ -193,7 +193,7 @@ group("all_components") {
       "//components/history/core/common",  # Should work, needs checking.
       "//components/history/core/test",  # Should work, needs checking.
       "//components/infobars/core",  # Should work, needs checking.
-      "//components/invalidation",  # Should work, needs checking.
+      "//components/invalidation/impl",  # Should work, needs checking.
       "//components/json_schema",  # Should work, needs checking.
       "//components/keyed_service/content",  # Blocked on content.
       "//components/navigation_interception",  # Blocked on content.
@@ -284,7 +284,7 @@ test("components_unittests") {
     "//components/domain_reliability:unit_tests",
     "//components/favicon_base:unit_tests",
     "//components/google/core/browser:unit_tests",
-    "//components/invalidation:unittests",
+    "//components/invalidation/impl:unittests",
     "//components/login:unit_tests",
     "//components/metrics:unit_tests",
     "//components/mime_util:unit_tests",