Default components to static libraries in GN build

chrome/browser/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/crypto.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//chrome/common/features.gni")
 import("//media/media_options.gni")
@@ skipping 1045 matching lines @@
     args = rebase_path(sources, root_build_dir) +
            rebase_path(outputs, root_build_dir)
   }
 } else {
   group("chrome_internal_resources_gen") {
     # Empty placeholder.
   }
 }
 
 # In GYP this is part of test_support_common.
-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
 
   # Always include this via the main test support target.
   visibility = [ "//chrome/test:test_support" ]
 
   sources = [
     "browsing_data/mock_browsing_data_appcache_helper.cc",
     "browsing_data/mock_browsing_data_appcache_helper.h",
     "browsing_data/mock_browsing_data_cache_storage_helper.cc",
     "browsing_data/mock_browsing_data_cache_storage_helper.h",
@@ skipping 286 matching lines @@
   # linking all of the test support.
   source_set("pepper_cdm_test_constants") {
     testonly = true
     visibility = [ "//chrome/*" ]
     sources = [
       "media/pepper_cdm_test_constants.cc",
       "media/pepper_cdm_test_constants.h",
     ]
   }
 }