Make base a static ibrary

base/BUILD.gn

 # Copyright (c) 2013 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/compiler/compiler.gni")
 import("//build/config/nacl/config.gni")
 import("//build/config/ui.gni")
 import("//build/nocompile.gni")
 import("//testing/test.gni")
 
@@ skipping 30 matching lines @@
 if (is_nacl_nonsfi) {
   # Must be in a config because of how GN orders flags (otherwise -Wall will
   # appear after this, and turn it back on).
   config("nacl_nonsfi_warnings") {
     # file_util_posix.cc contains a function which is not
     # being used by nacl_helper_nonsfi.
     cflags = [ "-Wno-unused-function" ]
   }
 }
 
-source_set("base_paths") {
-  sources = [
-    "base_paths.cc",
-    "base_paths.h",
-    "base_paths_android.cc",
-    "base_paths_android.h",
-    "base_paths_mac.h",
-    "base_paths_mac.mm",
-    "base_paths_posix.cc",
-    "base_paths_posix.h",
-    "base_paths_win.cc",
-    "base_paths_win.h",
-  ]
+if (is_nacl) {
+  # None of the files apply to nacl, and we can't make an empty static library.
+  group("base_paths") {
+  }
+} else {
+  static_library("base_paths") {
+    sources = [
+      "base_paths.cc",
+      "base_paths.h",
+      "base_paths_android.cc",
+      "base_paths_android.h",
+      "base_paths_mac.h",
+      "base_paths_mac.mm",
+      "base_paths_posix.cc",
+      "base_paths_posix.h",
+      "base_paths_win.cc",
+      "base_paths_win.h",
+    ]
 
-  if (is_android || is_mac || is_ios) {
-    sources -= [ "base_paths_posix.cc" ]
+    if (is_android || is_mac || is_ios) {
+      sources -= [ "base_paths_posix.cc" ]
+    }
+
+    configs += [ ":base_implementation" ]
+
+    deps = [
+      "//base/memory",
+      "//base/process",
+    ]
+
+    visibility = [ ":base" ]
   }
-
-  if (is_nacl) {
-    sources -= [
-      "base_paths.cc",
-      "base_paths_posix.cc",
-    ]
-  }
-
-  configs += [ ":base_implementation" ]
-
-  deps = [
-    "//base/memory",
-    "//base/process",
-  ]
-
-  visibility = [ ":base" ]
 }
 
-component("base") {
+# Base and everything it depends on should be a static library rather than
+# a source set. Base is more of a "library" in the classic sense in that many
+# small parts of it are used in many different contexts. This combined with a
+# few static initializers floating around means that dead code stripping
+# still leaves a lot of code behind that isn't always used. For example, this
+# saves more than 40K for a smaller target like chrome_elf.
+#
+# Use static libraries for the helper stuff as well like //base/debug since
+# those things refer back to base code, which will force base compilation units
+# to be linked in where they wouldn't have otherwise. This does not include
+# test code (test support and anything in the test directory) which should use
+# source_set as is recommended for GN targets).
+if (is_component_build) {
+  base_target_type = "shared_library"
+} else {
+  base_target_type = "static_library"
+}
+target(base_target_type, "base") {
   sources = [
     "allocator/allocator_extension.cc",
     "allocator/allocator_extension.h",
     "android/animation_frame_time_histogram.cc",
     "android/animation_frame_time_histogram.h",
     "android/apk_assets.cc",
     "android/apk_assets.h",
     "android/application_status_listener.cc",
     "android/application_status_listener.h",
     "android/base_jni_onload.cc",
@@ skipping 881 matching lines @@
     configs -= [ "//build/config/compiler:default_optimization" ]
     configs += [ "//build/config/compiler:optimize_max" ]
   }
 
   allow_circular_includes_from = public_deps
 }
 
 # This is the subset of files from base that should not be used with a dynamic
 # library. Note that this library cannot depend on base because base depends on
 # base_static.
-source_set("base_static") {
+static_library("base_static") {
   sources = [
     "base_switches.cc",
     "base_switches.h",
     "win/pe_image.cc",
     "win/pe_image.h",
   ]
 
   if (!is_debug) {
     configs -= [ "//build/config/compiler:default_optimization" ]
     configs += [ "//build/config/compiler:optimize_max" ]
@@ skipping 772 matching lines @@
 
   # GYP: //base.gyp:base_java_unittest_support
   android_library("base_java_unittest_support") {
     deps = [
       ":base_java",
     ]
     java_files =
         [ "test/android/java/src/org/chromium/base/ContentUriTestUtils.java" ]
   }
 }