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

tools/clang/blink_gc_plugin/tests/fields_illegal_tracing.txt

Index: tools/clang/blink_gc_plugin/tests/fields_illegal_tracing.txt
diff --git a/tools/clang/blink_gc_plugin/tests/fields_illegal_tracing.txt b/tools/clang/blink_gc_plugin/tests/fields_illegal_tracing.txt
index 61dc6a2fbe94af04748c75f0ef8c06fa1a55f3ba..5486505e18c65e9d75d090c953899381fc8cce3f 100644
--- a/tools/clang/blink_gc_plugin/tests/fields_illegal_tracing.txt
+++ b/tools/clang/blink_gc_plugin/tests/fields_illegal_tracing.txt
@@ -39,7 +39,7 @@ class HeapObject : public GarbageCollectedFinalized<HeapObject> {
     HeapLinkedHashSet<Member<HeapObject>>::const_iterator m_iterator6;
     ^
 fields_illegal_tracing.cpp:9:1: warning: [blink-gc] Class 'PartObject' has untraced or not traceable fields.
-void PartObject::trace(Visitor* visitor) {
+void PartObject::Trace(Visitor* visitor) {
 ^
 ./fields_illegal_tracing.h:37:5: note: [blink-gc] Untraceable field 'm_obj1' declared here:
     OwnPtr<HeapObject> m_obj1;
@@ -51,7 +51,7 @@ void PartObject::trace(Visitor* visitor) {
     std::unique_ptr<HeapObject> m_obj4;
     ^
 fields_illegal_tracing.cpp:16:1: warning: [blink-gc] Class 'HeapObject' has untraced or not traceable fields.
-void HeapObject::trace(Visitor* visitor) {
+void HeapObject::Trace(Visitor* visitor) {
 ^
 ./fields_illegal_tracing.h:51:5: note: [blink-gc] Untraceable field 'm_obj1' declared here:
     OwnPtr<HeapObject> m_obj1;