Revert of Make base a static ibrary

base/debug/BUILD.gn

 # Copyright (c) 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.
 
 import("//build/buildflag_header.gni")
 import("//build/config/compiler/compiler.gni")
 
-# Should be static library, see documentation on //base:base for discussion.
-static_library("debug") {
+source_set("debug") {
   sources = [
     "alias.cc",
     "alias.h",
     "asan_invalid_access.cc",
     "asan_invalid_access.h",
     "close_handle_hook_win.cc",
     "close_handle_hook_win.h",
     "crash_logging.cc",
     "crash_logging.h",
     "debugger.cc",
@@ skipping 61 matching lines @@
   ]
 
   visibility = [ "//base/*" ]
 }
 
 buildflag_header("debugging_flags") {
   header = "debugging_flags.h"
 
   flags = [ "ENABLE_PROFILING=$enable_profiling" ]
 }