Move error classification into the ssl_errors component

components/ssl_errors/BUILD.gn

 # Copyright 2015 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # GYP version: components/ssl_errors.gyp
 source_set("ssl_errors") {
   sources = [
+    "error_classification.cc",
+    "error_classification.h",
     "error_info.cc",
     "error_info.h",
   ]
 
   deps = [
     "//base",
     "//components/strings",
     "//net",
     "//ui/base",
   ]
 }
+
+source_set("unit_tests") {
+  testonly = true
+  sources = [
+    "error_classification_unittests.cc",
+  ]
+
+  deps = [
+    ":ssl_errors",
+    "//testing/gtest",
+  ]
+}