blink_gc_plugin: retire overloaded traceImpl detection and handling.

tools/clang/blink_gc_plugin/tests/trace_after_dispatch_impl_error.txt

Index: tools/clang/blink_gc_plugin/tests/trace_after_dispatch_impl_error.txt
diff --git a/tools/clang/blink_gc_plugin/tests/trace_after_dispatch_impl_error.txt b/tools/clang/blink_gc_plugin/tests/trace_after_dispatch_impl_error.txt
index 5637daa1fdf1fec50272782032a038009021599d..85f57af98a75c44d582c4b94f5f25bef28caf634 100644
--- a/tools/clang/blink_gc_plugin/tests/trace_after_dispatch_impl_error.txt
+++ b/tools/clang/blink_gc_plugin/tests/trace_after_dispatch_impl_error.txt
@@ -1,34 +1,34 @@
-trace_after_dispatch_impl_error.cpp:10:1: warning: [blink-gc] Missing dispatch to class 'TraceAfterDispatchInlinedDerived' in manual trace dispatch.
-inline void TraceAfterDispatchInlinedBase::TraceImpl(
+trace_after_dispatch_impl_error.cpp:9:1: warning: [blink-gc] Missing dispatch to class 'TraceAfterDispatchInlinedDerived' in manual trace dispatch.
+inline void TraceAfterDispatchInlinedBase::Trace(Visitor* visitor) {
 ^
-trace_after_dispatch_impl_error.cpp:35:1: warning: [blink-gc] Missing dispatch to class 'TraceAfterDispatchExternDerived' in manual trace dispatch.
-inline void TraceAfterDispatchExternBase::TraceImpl(VisitorDispatcher visitor) {
+trace_after_dispatch_impl_error.cpp:24:1: warning: [blink-gc] Missing dispatch to class 'TraceAfterDispatchExternDerived' in manual trace dispatch.
+void TraceAfterDispatchExternBase::Trace(Visitor* visitor) {
 ^
 In file included from trace_after_dispatch_impl_error.cpp:5:
-./trace_after_dispatch_impl_error.h:39:3: warning: [blink-gc] Class 'TraceAfterDispatchInlinedBase' has untraced fields that require tracing.
-  void TraceAfterDispatchImpl(VisitorDispatcher visitor) {
+./trace_after_dispatch_impl_error.h:28:3: warning: [blink-gc] Class 'TraceAfterDispatchInlinedBase' has untraced fields that require tracing.
+  void TraceAfterDispatch(Visitor* visitor) {
   ^
-./trace_after_dispatch_impl_error.h:44:3: note: [blink-gc] Untraced field 'x_base_' declared here:
+./trace_after_dispatch_impl_error.h:34:3: note: [blink-gc] Untraced field 'x_base_' declared here:
   Member<X> x_base_;
   ^
-./trace_after_dispatch_impl_error.h:58:3: warning: [blink-gc] Base class 'TraceAfterDispatchInlinedBase' of derived class 'TraceAfterDispatchInlinedDerived' requires tracing.
-  void TraceAfterDispatchImpl(VisitorDispatcher visitor) {
+./trace_after_dispatch_impl_error.h:41:3: warning: [blink-gc] Base class 'TraceAfterDispatchInlinedBase' of derived class 'TraceAfterDispatchInlinedDerived' requires tracing.
+  void TraceAfterDispatch(Visitor* visitor) {
   ^
-./trace_after_dispatch_impl_error.h:58:3: warning: [blink-gc] Class 'TraceAfterDispatchInlinedDerived' has untraced fields that require tracing.
-./trace_after_dispatch_impl_error.h:62:3: note: [blink-gc] Untraced field 'x_derived_' declared here:
+./trace_after_dispatch_impl_error.h:41:3: warning: [blink-gc] Class 'TraceAfterDispatchInlinedDerived' has untraced fields that require tracing.
+./trace_after_dispatch_impl_error.h:46:3: note: [blink-gc] Untraced field 'x_derived_' declared here:
   Member<X> x_derived_;
   ^
-trace_after_dispatch_impl_error.cpp:55:1: warning: [blink-gc] Class 'TraceAfterDispatchExternBase' has untraced fields that require tracing.
-inline void TraceAfterDispatchExternBase::TraceAfterDispatchImpl(
+trace_after_dispatch_impl_error.cpp:34:1: warning: [blink-gc] Class 'TraceAfterDispatchExternBase' has untraced fields that require tracing.
+void TraceAfterDispatchExternBase::TraceAfterDispatch(Visitor* visitor) {
 ^
-./trace_after_dispatch_impl_error.h:84:3: note: [blink-gc] Untraced field 'x_base_' declared here:
+./trace_after_dispatch_impl_error.h:60:3: note: [blink-gc] Untraced field 'x_base_' declared here:
   Member<X> x_base_;
   ^
-trace_after_dispatch_impl_error.cpp:70:1: warning: [blink-gc] Base class 'TraceAfterDispatchExternBase' of derived class 'TraceAfterDispatchExternDerived' requires tracing.
-inline void TraceAfterDispatchExternDerived::TraceAfterDispatchImpl(
+trace_after_dispatch_impl_error.cpp:38:1: warning: [blink-gc] Base class 'TraceAfterDispatchExternBase' of derived class 'TraceAfterDispatchExternDerived' requires tracing.
+void TraceAfterDispatchExternDerived::TraceAfterDispatch(Visitor* visitor) {
 ^
-trace_after_dispatch_impl_error.cpp:70:1: warning: [blink-gc] Class 'TraceAfterDispatchExternDerived' has untraced fields that require tracing.
-./trace_after_dispatch_impl_error.h:98:3: note: [blink-gc] Untraced field 'x_derived_' declared here:
+trace_after_dispatch_impl_error.cpp:38:1: warning: [blink-gc] Class 'TraceAfterDispatchExternDerived' has untraced fields that require tracing.
+./trace_after_dispatch_impl_error.h:70:3: note: [blink-gc] Untraced field 'x_derived_' declared here:
   Member<X> x_derived_;
   ^
 8 warnings generated.