Output aesthetics tweaks: extra `__NEWLINE__` tokens.

This CL has been manually tested by looking at `impls_cc_api.h`
generated from `cc_bindings_from_rs/test/impls/impl.rs`.  Ideally the
effects of this CL would be covered by automated `test/golden` tests but
implementing them is blocked by an unrelated issue.

PiperOrigin-RevId: 509350740

cc_bindings_from_rs/bindings.rs

diff --git a/cc_bindings_from_rs/bindings.rs b/cc_bindings_from_rs/bindings.rs
index c5858c7..5382360 100644
--- a/cc_bindings_from_rs/bindings.rs
+++ b/cc_bindings_from_rs/bindings.rs
@@ -710,10 +710,12 @@
         CcSnippet {
             prereqs,
             tokens: quote! {
+                __NEWLINE__
                 #doc_comment
                 #static_ #extern_c_or_inline #cc_ret_type #cc_fn_name (
                         #( #cc_arg_types #cc_arg_names ),*
                 );
+                __NEWLINE__
             },
         }
     };
@@ -739,6 +741,7 @@
         let cc = CcSnippet {
             prereqs,
             tokens: quote! {
+                __NEWLINE__
                 namespace __crubit_internal {
                     extern "C" #cc_ret_type #cc_exported_name (
                             #( #cc_arg_types #cc_arg_names ),*
@@ -748,6 +751,7 @@
                         #( #cc_arg_types #cc_arg_names ),* ) {
                     return __crubit_internal :: #cc_exported_name( #( #thunk_args ),* );
                 }
+                __NEWLINE__
             },
         };
 
@@ -1052,17 +1056,20 @@
                         // TODO(b/258233850): Emit individual fields.
                         unsigned char opaque_blob_of_bytes[#size];
                 };
+                __NEWLINE__
             },
         }
     };
     let impl_details = {
         let mut cc = CcSnippet::new(quote! {
+            __NEWLINE__
             static_assert(
                 sizeof(#cc_name) == #size,
                 "Verify that struct layout didn't change since this header got generated");
             static_assert(
                 alignof(#cc_name) == #alignment,
                 "Verify that struct layout didn't change since this header got generated");
+            __NEWLINE__
         });
         cc.prereqs.defs.insert(local_def_id);
         let rs = {
@@ -1286,10 +1293,14 @@
         let includes = format_cc_includes(&includes);
         let ordered_cc = format_namespace_bound_cc_tokens(ordered_cc);
         quote! {
-            #includes __NEWLINE__
+            #includes
+            __NEWLINE__ __NEWLINE__
             namespace #crate_name {
+                __NEWLINE__
                 #ordered_cc
+                __NEWLINE__
             }
+            __NEWLINE__
         }
     };
 

cc_bindings_from_rs/cc_bindings_from_rs.rs

diff --git a/cc_bindings_from_rs/cc_bindings_from_rs.rs b/cc_bindings_from_rs/cc_bindings_from_rs.rs
index 3027780..090cb66 100644
--- a/cc_bindings_from_rs/cc_bindings_from_rs.rs
+++ b/cc_bindings_from_rs/cc_bindings_from_rs.rs
@@ -288,10 +288,13 @@
 #pragma once
 
 namespace test_crate {
-namespace public_module {"#,
+
+namespace public_module {
+"#,
  // TODO(b/261185414): Avoid assuming that all source code paths are google3 paths.
 format!("// Generated from: google3{temp_dir_str}/test_crate.rs;l=2"),
 r#"inline void public_function();
+
 namespace __crubit_internal {
 extern "C" void
 __crubit_thunk__ANY_IDENTIFIER_CHARACTERS();
@@ -300,8 +303,11 @@
   return __crubit_internal::
       __crubit_thunk__ANY_IDENTIFIER_CHARACTERS();
 }
+
 }  // namespace public_module
-}  // namespace test_crate"#
+
+}  // namespace test_crate
+"#
             ),
         );