Add more components_unittests to GN build

components/leveldb_proto/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("leveldb_proto") {
   sources = [
     "leveldb_database.cc",
     "leveldb_database.h",
     "proto_database.h",
     "proto_database_impl.h",
   ]
 
   deps = [
     "//base",
     "//third_party/leveldatabase",
   ]
 }
 
 source_set("test_support") {
   sources = [
     "testing/fake_db.h",
   ]
 
-  deps = [
+  public_deps = [
     ":leveldb_proto",
     "//components/leveldb_proto/testing/proto",
   ]
 }
+
+source_set("unit_tests") {
+  testonly = true
+  sources = [
+    "proto_database_impl_unittest.cc",
+  ]
+  deps = [
+    ":test_support",
+    "//testing/gmock",
+    "//testing/gtest",
+  ]
+}