Add WebDataConsumerHandle::debugName()

public/platform/WebDataConsumerHandle.h

Index: public/platform/WebDataConsumerHandle.h
diff --git a/public/platform/WebDataConsumerHandle.h b/public/platform/WebDataConsumerHandle.h
index cba7e9746f4ebf8ed6cb0a4fd84bdc97ece00f89..3b86e4fd2e87b7a1f67bb3cd78f3038d220a9e3b 100644
--- a/public/platform/WebDataConsumerHandle.h
+++ b/public/platform/WebDataConsumerHandle.h
@@ -113,6 +113,9 @@ public:
     PassOwnPtr<Reader> obtainReader(Client* client) { return adoptPtr(obtainReaderInternal(client)); }
 #endif
 
+    // Returns a string literal (e.g. class name) for debugging only.
+    virtual const char* debugName() const { return "WebDataConsumerHandle"; }
+
 private:
     // The caller takes ownership of the returned object.
     virtual Reader* obtainReaderInternal(Client* client)