Default chromium_style to off.

This CL changes the gn args to disable the `chromium-style` plugin by
default for Tint.

Change-Id: Icc3e0edf8ebad5ffcaf8ca37b40024b233da296a
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/91002
Kokoro: Kokoro <noreply+kokoro@google.com>
Auto-Submit: Dan Sinclair <dsinclair@chromium.org>
Reviewed-by: Ben Clayton <bclayton@google.com>
Commit-Queue: Ben Clayton <bclayton@google.com>
diff --git a/.gn b/.gn
index 2bc6b1c..94c45fb 100644
--- a/.gn
+++ b/.gn
@@ -18,3 +18,7 @@
 script_executable = "python3"
 
 check_targets = [ "//*" ]
+
+default_args = {
+  clang_use_chrome_plugins = false
+}