Cleanup headless templates and message_dispatcher.h.

headless/lib/browser/headless_devtools_client_impl.h

Index: headless/lib/browser/headless_devtools_client_impl.h
diff --git a/headless/lib/browser/headless_devtools_client_impl.h b/headless/lib/browser/headless_devtools_client_impl.h
index a9e270a4b4ff527dc2e21c0881104bc4fb98348c..c7c248b472ef4f8d8fa3b1be2f35c8eecfd9cdd4 100644
--- a/headless/lib/browser/headless_devtools_client_impl.h
+++ b/headless/lib/browser/headless_devtools_client_impl.h
@@ -106,11 +106,7 @@ class HeadlessDevToolsClientImpl : public HeadlessDevToolsClient,
                    base::Callback<void(const base::Value&)> callback) override;
   void SendMessage(const char* method,
                    std::unique_ptr<base::Value> params,
-                   base::Callback<void()> callback) override;
-  void SendMessage(const char* method,
-                   base::Callback<void(const base::Value&)> callback) override;
-  void SendMessage(const char* method,
-                   base::Callback<void()> callback) override;
+                   base::Closure callback) override;
   void RegisterEventHandler(
       const char* method,
       base::Callback<void(const base::Value&)> callback) override;
@@ -125,13 +121,13 @@ class HeadlessDevToolsClientImpl : public HeadlessDevToolsClient,
   struct Callback {
     Callback();
     Callback(Callback&& other);
-    explicit Callback(base::Callback<void()> callback);
+    explicit Callback(base::Closure callback);
     explicit Callback(base::Callback<void(const base::Value&)> callback);
     ~Callback();
 
     Callback& operator=(Callback&& other);
 
-    base::Callback<void()> callback;
+    base::Closure callback;
     base::Callback<void(const base::Value&)> callback_with_result;
   };
 
@@ -144,9 +140,6 @@ class HeadlessDevToolsClientImpl : public HeadlessDevToolsClient,
                              std::unique_ptr<base::Value> params,
                              CallbackType callback);
 
-  template <typename CallbackType>
-  void SendMessageWithoutParams(const char* method, CallbackType callback);
-
   bool DispatchMessageReply(const base::DictionaryValue& message_dict);
 
   using EventHandler = base::Callback<void(const base::Value&)>;