[DevTools] Merge InspectorFrontendClientImpl into WebDevToolsFrontendImpl and remove unused code.

Source/core/inspector/InspectorFrontendClient.h

Index: Source/core/inspector/InspectorFrontendClient.h
diff --git a/Source/core/inspector/InspectorFrontendClient.h b/Source/core/inspector/InspectorFrontendClient.h
index eedb6d0336fa4cb00fe91f2bd2713fb16ad92509..c532704bce771c0a075978da9f0fb2c01797a65e 100644
--- a/Source/core/inspector/InspectorFrontendClient.h
+++ b/Source/core/inspector/InspectorFrontendClient.h
@@ -31,17 +31,14 @@
 #ifndef InspectorFrontendClient_h
 #define InspectorFrontendClient_h
 
-#include "platform/heap/Handle.h"
 #include "wtf/Forward.h"
 
 namespace blink {
 
-class InspectorFrontendClient : public NoBaseWillBeGarbageCollectedFinalized<InspectorFrontendClient> {
+class InspectorFrontendClient {
 public:
     virtual ~InspectorFrontendClient() { }
 
-    virtual void trace(Visitor*) { }
-
     virtual void windowObjectCleared() = 0;
 
     virtual void sendMessageToBackend(const String&) = 0;