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

tools/clang/blink_gc_plugin/tests/traceimpl_overloaded_error.txt

Index: tools/clang/blink_gc_plugin/tests/traceimpl_overloaded_error.txt
diff --git a/tools/clang/blink_gc_plugin/tests/traceimpl_overloaded_error.txt b/tools/clang/blink_gc_plugin/tests/traceimpl_overloaded_error.txt
index 644f9f0c11a603ec2dd9eade3784f5bb82cd45d9..b603a0861ffb69306ee0ee3aa09c1eead487e343 100644
--- a/tools/clang/blink_gc_plugin/tests/traceimpl_overloaded_error.txt
+++ b/tools/clang/blink_gc_plugin/tests/traceimpl_overloaded_error.txt
@@ -1,25 +1,25 @@
 In file included from traceimpl_overloaded_error.cpp:5:
 ./traceimpl_overloaded_error.h:27:3: warning: [blink-gc] Class 'InlinedBase' has untraced fields that require tracing.
-  void traceImpl(VisitorDispatcher visitor) {
+  void TraceImpl(VisitorDispatcher visitor) {
   ^
 ./traceimpl_overloaded_error.h:31:3: note: [blink-gc] Untraced field 'x_base_' declared here:
   Member<X> x_base_;
   ^
 ./traceimpl_overloaded_error.h:43:3: warning: [blink-gc] Base class 'InlinedBase' of derived class 'InlinedDerived' requires tracing.
-  void traceImpl(VisitorDispatcher visitor) {
+  void TraceImpl(VisitorDispatcher visitor) {
   ^
 ./traceimpl_overloaded_error.h:43:3: warning: [blink-gc] Class 'InlinedDerived' has untraced fields that require tracing.
 ./traceimpl_overloaded_error.h:47:3: note: [blink-gc] Untraced field 'x_derived_' declared here:
   Member<X> x_derived_;
   ^
 traceimpl_overloaded_error.cpp:18:1: warning: [blink-gc] Class 'ExternBase' has untraced fields that require tracing.
-inline void ExternBase::traceImpl(VisitorDispatcher visitor) {
+inline void ExternBase::TraceImpl(VisitorDispatcher visitor) {
 ^
 ./traceimpl_overloaded_error.h:59:3: note: [blink-gc] Untraced field 'x_base_' declared here:
   Member<X> x_base_;
   ^
 traceimpl_overloaded_error.cpp:31:1: warning: [blink-gc] Base class 'ExternBase' of derived class 'ExternDerived' requires tracing.
-inline void ExternDerived::traceImpl(VisitorDispatcher visitor) {
+inline void ExternDerived::TraceImpl(VisitorDispatcher visitor) {
 ^
 traceimpl_overloaded_error.cpp:31:1: warning: [blink-gc] Class 'ExternDerived' has untraced fields that require tracing.
 ./traceimpl_overloaded_error.h:71:3: note: [blink-gc] Untraced field 'x_derived_' declared here: