Convert some GN test support targets to static libs.

components/open_from_clipboard/BUILD.gn

 # Copyright 2015 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("open_from_clipboard") {
+static_library("open_from_clipboard") {
   sources = [
     "clipboard_recent_content.cc",
     "clipboard_recent_content.h",
     "clipboard_recent_content_ios.h",
     "clipboard_recent_content_ios.mm",
   ]
 
   deps = [
     "//base",
     "//url",
   ]
 }
 
-source_set("test_support") {
+static_library("test_support") {
   testonly = true
   sources = [
     "fake_clipboard_recent_content.cc",
     "fake_clipboard_recent_content.h",
   ]
 
   deps = [
     ":open_from_clipboard",
     "//base",
     "//url",
   ]
 }
 
 source_set("unit_tests") {
   testonly = true
   sources = [
     "clipboard_recent_content_ios_unittest.mm",
   ]
 
   deps = [
     ":open_from_clipboard",
     "//base",
     "//testing/gtest",
   ]
 }