Remove extensions_tests.gyp[i]

extensions/utility/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.
 
 import("//build/config/features.gni")
 import("//extensions/extensions.gni")
 
 assert(enable_extensions)
 
 # GYP version: extensions/extensions.gyp:extensions_utility
 source_set("utility") {
   sources = rebase_path(extensions_gypi_values.extensions_utility_sources,
                         ".",
                         "//extensions")
 
   # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
   configs += [ "//build/config/compiler:no_size_t_to_int_warning" ]
 
   deps = [
     "//content/public/common",
     "//content/public/utility",
     "//extensions/common",
     "//skia",
   ]
 }
+
+source_set("unit_tests") {
+  testonly = true
+  sources = [
+    "unpacker_unittest.cc",
+  ]
+  deps = [
+    ":utility",
+    "//base",
+    "//extensions:test_support",
+    "//extensions/common",
+    "//extensions/strings",
+    "//testing/gtest",
+    "//third_party/zlib:zip",
+    "//ui/base",
+  ]
+}