[Cronet] Enforce implementation does not call through API classes

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 1079 matching lines @@
       rebase_path("$root_out_dir/obj/base/base/*.o", root_build_dir),
       "--stamp",
       rebase_path(outputs[0], root_build_dir),
     ]
     deps = [
       "//base:base",
     ]
   }
 }
 
+# Enforce restrictions for API<->impl boundary.
+action("api_static_checks") {
+  script = "//components/cronet/tools/api_static_checks.py"
+  outputs = [
+    "$target_gen_dir/$target_name.stamp",
+  ]
+  args = [
+    "--api_jar",
+    rebase_path(
+        "$root_out_dir/lib.java/components/cronet/android/cronet_api.jar",
+        root_build_dir),
+    "--impl_jar",
+    rebase_path(
+        "$root_out_dir/lib.java/components/cronet/android/cronet_impl_common_java.jar",
+        root_build_dir),
+    "--impl_jar",
+    rebase_path(
+        "$root_out_dir/lib.java/components/cronet/android/cronet_impl_platform_java.jar",
+        root_build_dir),
+    "--impl_jar",
+    rebase_path(
+        "$root_out_dir/lib.java/components/cronet/android/cronet_impl_native_java.jar",
+        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",
+  ]
+}
+
 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" ]
     }
   }
 }