Add more components_unittests to GN build

components/json_schema/BUILD.gn

Index: components/json_schema/BUILD.gn
diff --git a/components/json_schema/BUILD.gn b/components/json_schema/BUILD.gn
index 8bcb7d52e62af3782ab062cc0bd5e962d3901a32..4e7b4355974958f567a2830def649e601473b68a 100644
--- a/components/json_schema/BUILD.gn
+++ b/components/json_schema/BUILD.gn
@@ -2,7 +2,7 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-static_library("json_schema") {
+source_set("json_schema") {
   sources = [
     "json_schema_constants.cc",
     "json_schema_constants.h",
@@ -15,3 +15,16 @@ static_library("json_schema") {
     "//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",
+  ]
+}