Style guide: Add text about C and non-compliant C++ code


Change-Id: I64a64a4f138b6c8aa24ad2266284024d50163908
Reviewed-by: Niels Möller <>
Commit-Queue: Karl Wiberg <>
Cr-Commit-Position: refs/heads/master@{#19680}
diff --git a/ b/
index 6cf5f45..17e9fe9 100644
--- a/
+++ b/
@@ -10,7 +10,27 @@
+Some older parts of the code violate the style guide in various ways.
+* If making small changes to such code, follow the style guide when
+  it’s reasonable to do so, but in matters of formatting etc., it is
+  often better to be consistent with the surrounding code.
+* If making large changes to such code, consider first cleaning it up
+  in a separate CL.
 ### Exceptions
 There are no exceptions yet. If and when exceptions are adopted,
-they'll be listed here.
+they’ll be listed here.
+## C
+There’s a substantial chunk of legacy C code in WebRTC, and a lot of
+it is old enough that it violates the parts of the C++ style guide
+that also applies to C (naming etc.) for the simple reason that it
+pre-dates the use of the current C++ style guide for this code base.
+* If making small changes to C code, mimic the style of the
+  surrounding code.
+* If making large changes to C code, consider converting the whole
+  thing to C++ first.