Add use-chromium-style-naming option to Blink GC plugin.

tools/clang/blink_gc_plugin/tests/garbage_collected_mixin.txt

Index: tools/clang/blink_gc_plugin/tests/garbage_collected_mixin.txt
diff --git a/tools/clang/blink_gc_plugin/tests/garbage_collected_mixin.txt b/tools/clang/blink_gc_plugin/tests/garbage_collected_mixin.txt
index 4051a6a0f73b420a98fcebc1693dd3aa92d8002a..a14074f8d2266e6e184da1f91c4e96b4f0352bae 100644
--- a/tools/clang/blink_gc_plugin/tests/garbage_collected_mixin.txt
+++ b/tools/clang/blink_gc_plugin/tests/garbage_collected_mixin.txt
@@ -1,10 +1,10 @@
 garbage_collected_mixin.cpp:9:1: warning: [blink-gc] Class 'Mixin' has untraced fields that require tracing.
-void Mixin::trace(Visitor* visitor)
+void Mixin::Trace(Visitor* visitor)
 ^
 ./garbage_collected_mixin.h:16:5: note: [blink-gc] Untraced field 'm_self' declared here:
     Member<Mixin> m_self;
     ^
 garbage_collected_mixin.cpp:14:1: warning: [blink-gc] Base class 'Mixin' of derived class 'HeapObject' requires tracing.
-void HeapObject::trace(Visitor* visitor)
+void HeapObject::Trace(Visitor* visitor)
 ^
 2 warnings generated.