Convert some GN test support targets to static libs.

ui/gfx/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/ui.gni")
 import("//testing/test.gni")
 
 if (is_android) {
   import("//build/config/android/config.gni")
   import("//build/config/android/rules.gni")
@@ skipping 519 matching lines @@
   }
 
   defines = [ "GFX_IMPLEMENTATION" ]
 
   deps = [
     "//base",
     "//ui/gfx/geometry",
   ]
 }
 
-source_set("test_support") {
+static_library("test_support") {
   testonly = true
   sources = [
     "image/image_unittest_util.cc",
     "image/image_unittest_util.h",
     "image/image_unittest_util_ios.mm",
     "image/image_unittest_util_mac.mm",
     "test/fontconfig_util_linux.cc",
     "test/fontconfig_util_linux.h",
     "test/gfx_util.cc",
     "test/gfx_util.h",
@@ skipping 178 matching lines @@
 if (is_android) {
   generate_jni("gfx_jni_headers") {
     sources = [
       "../android/java/src/org/chromium/ui/gfx/BitmapHelper.java",
       "../android/java/src/org/chromium/ui/gfx/DeviceDisplayInfo.java",
       "../android/java/src/org/chromium/ui/gfx/ViewConfigurationHelper.java",
     ]
     jni_package = "gfx"
   }
 }