[Cronet] Enforce implementation does not call through API classes

components/cronet/android/BUILD.gn

Index: components/cronet/android/BUILD.gn
diff --git a/components/cronet/android/BUILD.gn b/components/cronet/android/BUILD.gn
index a15f26da73d0884f6b9da8c0775830a616bccaf4..d8cd8e88e8836c8b3d53ae4fce74f48b63fc947f 100644
--- a/components/cronet/android/BUILD.gn
+++ b/components/cronet/android/BUILD.gn
@@ -1097,11 +1097,46 @@ if (target_cpu == "arm" && arm_version == 7 && !arm_use_neon) {
   }
 }
 
+# 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",