[Cronet] Enforce Cronet API never modified, only grown

components/cronet/android/BUILD.gn

 # 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("//build/buildflag_header.gni")
 import("//build/config/android/config.gni")
 import("//build/config/android/rules.gni")
 import("//build/util/process_version.gni")
 import("//build/util/version.gni")
 import("//testing/test.gni")
@@ skipping 1111 matching lines @@
         root_build_dir),
     "--stamp",
     rebase_path(outputs[0], root_build_dir),
   ]
   deps = [
     ":cronet_api_java",
     ":cronet_impl_common_java",
     ":cronet_impl_native_java",
     ":cronet_impl_platform_java",
   ]
+  sources = [
+    "//components/cronet/android/api.txt",
+    "//components/cronet/android/api_version.txt",
+    "//components/cronet/tools/update_api.py",
+  ]
 }
 
 group("cronet_package") {
   # Enforce that arm_use_neon==false when building for ARMv7 by
   # not including any deps in cronet_package target otherwise.
   if (!(target_cpu == "arm" && arm_version == 7) || !arm_use_neon) {
     deps = [
       ":api_static_checks",
       ":cronet_combine_proguard_flags",
       ":cronet_package_copy",
       ":cronet_package_copy_native_lib",
       ":cronet_package_copy_native_lib_unstripped",
       ":generate_javadoc",
       ":generate_licenses",
       ":jar_cronet_api_source",
       ":jar_cronet_impl_common_java_source",
       ":jar_cronet_impl_native_java_source",
       ":jar_cronet_impl_platform_java_source",
       ":jar_cronet_sample_source",
       ":repackage_extracted_jars",
     ]
     if (current_cpu == "arm" && arm_version == 7) {
       deps += [ ":enforce_no_neon" ]
     }
   }
 }