Make large test_support targets static libraries.

content/test/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/chrome_build.gni")
 import("//build/config/compiler/compiler.gni")
 import("//build/config/crypto.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//build_overrides/v8.gni")
 import("//mojo/public/tools/bindings/mojom.gni")
 import("//testing/libfuzzer/fuzzer_test.gni")
 import("//testing/test.gni")
 
 content_tests_gypi_values =
     exec_script("//build/gypi_to_gn.py",
                 [
                   rebase_path("../content_tests.gypi"),
                   "--replace=<(SHARED_INTERMEDIATE_DIR)=$root_gen_dir",
                 ],
                 "scope",
                 [ "../content_tests.gypi" ])
 
 # GYP version //content/content_tests.gypi:test_support_content
-source_set("test_support") {
+#
+# Use a static library here because many test binaries depend on this but don't
+# require many files from it. This makes linking more efficient.
+static_library("test_support") {
   testonly = true
 
   # See comment at the top of //content/BUILD.gn for why this is disabled in
   # component builds.
   if (is_component_build) {
     check_includes = false
   }
 
   configs += [
     "//build/config:precompiled_headers",
@@ skipping 872 matching lines @@
 
 fuzzer_test("renderer_fuzzer") {
   sources = [
     "renderer_fuzzer.cc",
   ]
   deps = [
     ":test_support",
     "//content/shell:content_shell_lib",
   ]
 }