skiaserve: Add /quitquitquit handler. Will be used in the hosted debugger.

tools/skiaserve/urlhandlers/UrlHandler.h

 /*
  * Copyright 2016 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkColor.h"
 
 struct MHD_Connection;
@@ skipping 136 matching lines @@
  * Posting to /srgbMode/0 causes SkColor to be linear, /colorMode/1
  * causes SkColor to be sRGB;
  */
 class SRGBModeHandler : public UrlHandler {
 public:
     bool canHandle(const char* method, const char* url) override;
     int handle(Request* request, MHD_Connection* connection,
                const char* url, const char* method,
                const char* upload_data, size_t* upload_data_size) override;
 };
+
+class QuitHandler : public UrlHandler {
+public:
+    bool canHandle(const char* method, const char* url) override;
+    int handle(Request* request, MHD_Connection* connection,
+               const char* url, const char* method,
+               const char* upload_data, size_t* upload_data_size) override;
+};
+