add /img/n/m endpoint to skiaserve

tools/skiaserve/urlhandlers/ImgHandler.cpp

Index: tools/skiaserve/urlhandlers/ImgHandler.cpp
diff --git a/tools/skiaserve/urlhandlers/ImgHandler.cpp b/tools/skiaserve/urlhandlers/ImgHandler.cpp
index 3e390fe8325ae644426d395b63c643581851d140..a0e58bcc4dfec06037dff9550853a4c89541b8ed 100644
--- a/tools/skiaserve/urlhandlers/ImgHandler.cpp
+++ b/tools/skiaserve/urlhandlers/ImgHandler.cpp
@@ -25,19 +25,22 @@ int ImgHandler::handle(Request* request, MHD_Connection* connection,
     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");
 }