Revert of Add more components_unittests to GN build

components/json_schema/BUILD.gn

 # Copyright 2014 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("json_schema") {
+static_library("json_schema") {
   sources = [
     "json_schema_constants.cc",
     "json_schema_constants.h",
     "json_schema_validator.cc",
     "json_schema_validator.h",
   ]
 
   deps = [
     "//base",
     "//third_party/re2",
   ]
 }
-
-source_set("unit_tests") {
-  testonly = true
-  sources = [
-    "json_schema_validator_unittest.cc",
-    "json_schema_validator_unittest_base.cc",
-    "json_schema_validator_unittest_base.h",
-  ]
-  deps = [
-    ":json_schema",
-    "//testing/gtest",
-  ]
-}