Refactor base's proguard flags to be more usable by cronet

chrome/android/chrome_public_apk_tmpl.gni

 # Copyright 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("//base/android/linker/config.gni")
 import("//build/config/android/rules.gni")
 import("//chrome/common/features.gni")
 import("//third_party/leakcanary/config.gni")
 import("channel.gni")
 
@@ skipping 31 matching lines @@
 
     if (is_java_debug) {
       enable_multidex = true
     } else {
       proguard_enabled = true
       if (!defined(proguard_configs)) {
         proguard_configs = []
       }
       proguard_configs += [
         "//chrome/android/java/proguard.flags",
-        "//base/android/base_proguard_config.flags",
-        "//base/android/release_proguard_config.flags",
+        "//base/android/proguard/chromium_apk.flags",
+        "//base/android/proguard/chromium_code.flags",
       ]
     }
 
     if (!defined(use_chromium_linker)) {
       use_chromium_linker = chrome_public_apk_use_chromium_linker
     }
 
     if (use_chromium_linker) {
       if (!defined(load_library_from_apk)) {
         load_library_from_apk = chrome_public_apk_load_library_from_apk
       }
 
       if (!defined(enable_relocation_packing)) {
         enable_relocation_packing = chrome_public_apk_use_relocation_packer
       }
     }
   }
 }