add /img/n/m endpoint to skiaserve

tools/skiaserve/urlhandlers/ImgHandler.cpp

 /*
  * 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 "UrlHandler.h"
 
 #include "microhttpd.h"
 #include "../Request.h"
 #include "../Response.h"
 
 using namespace Response;
 
 bool ImgHandler::canHandle(const char* method, const char* url) {
     static const char* kBasePath = "/img";
     return 0 == strcmp(method, MHD_HTTP_METHOD_GET) &&
            0 == strncmp(url, kBasePath, strlen(kBasePath));
 }
 
 int ImgHandler::handle(Request* request, MHD_Connection* connection,
                        const char* url, const char* method,
                        const char* upload_data, size_t* upload_data_size) {
     SkTArray<SkString> commands;
     SkStrSplit(url, "/", &commands);
 
-    if (!request->hasPicture() || commands.count() > 2) {
+    if (!request->hasPicture() || commands.count() > 3) {
         return MHD_NO;
     }
 
-    int n;
+    int n, m = -1;
     // /img or /img/N
     if (commands.count() == 1) {
         n = request->fDebugCanvas->getSize() - 1;
+    } else if (commands.count() == 2) {
+        sscanf(commands[1].c_str(), "%d", &n);
     } else {
         sscanf(commands[1].c_str(), "%d", &n);
+        sscanf(commands[2].c_str(), "%d", &m);
     }
 
-    SkAutoTUnref<SkData> data(request->drawToPng(n));
+    SkAutoTUnref<SkData> data(request->drawToPng(n, m));
     return SendData(connection, data, "image/png");
 }