Reduce chrome.dll size by careful use of static_library

content/child/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("//build/config/ui.gni")
 import("//content/child/child.gni")
 
-source_set("child") {
+if (is_component_build) {
+  link_target_type = "source_set"
+} else {
+  link_target_type = "static_library"
+}
+target(link_target_type, "child") {
   # Targets external to content should always link to the public API.
   # Internal targets can link to this but only if they're child processes
   # (i.e. not content/browser or content/common) and only if they're inside the
   # content component (i.e. not content/test or content/shell).
   visibility = [
     ":*",
     "//content/gpu/*",
     "//content/ppapi_plugin/*",
     "//content/public/child:child_sources",
     "//content/renderer/*",
@@ skipping 81 matching lines @@
 
 # See comment at the top of //content/BUILD.gn for how this works.
 group("for_content_tests") {
   visibility = [ "//content/test/*" ]
   if (!is_component_build) {
     public_deps = [
       ":child",
     ]
   }
 }