Move Cast certificate verification code from extensions to components.

components/cast_certificate/BUILD.gn

+# Copyright 2016 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.
+
+source_set("cast_certificate") {
+  sources = [
+    "cast_cert_validator.cc",
+    "cast_cert_validator.h",
+    "cast_root_ca_cert_der-inc.h",
+    "eureka_root_ca_der-inc.h",
+  ]
+  deps = [
+    "//base",
+    "//net",
+  ]
+}
+
+source_set("test_support") {
+  testonly = true
+  sources = [
+    "cast_cert_validator_test_helpers.cc",
+    "cast_cert_validator_test_helpers.h",
+  ]
+  deps = [
+    ":cast_certificate",
+    "//base",
+    "//net",
+    "//testing/gtest",
+  ]
+}
+
+source_set("unit_tests") {
+  testonly = true
+  sources = [
+    "cast_cert_validator_unittest.cc",
+  ]
+  deps = [
+    ":cast_certificate",
+    ":test_support",
+    "//base",
+    "//net",
+    "//testing/gtest",
+  ]
+}