add /img/n/m endpoint to skiaserve

tools/skiaserve/Request.cpp

Index: tools/skiaserve/Request.cpp
diff --git a/tools/skiaserve/Request.cpp b/tools/skiaserve/Request.cpp
index 92e18fda51fd233fd8ed4c7d23cac941dae04be5..8ffcc36f77781a685d0303913faf5d1ce081f5e6 100644
--- a/tools/skiaserve/Request.cpp
+++ b/tools/skiaserve/Request.cpp
@@ -93,13 +93,13 @@ SkCanvas* Request::getCanvas() {
     return target;
 }
 
-void Request::drawToCanvas(int n) {
+void Request::drawToCanvas(int n, int m) {
     SkCanvas* target = this->getCanvas();
-    fDebugCanvas->drawTo(target, n);
+    fDebugCanvas->drawTo(target, n, m);
 }
 
-SkData* Request::drawToPng(int n) {
-    this->drawToCanvas(n);
+SkData* Request::drawToPng(int n, int m) {
+    this->drawToCanvas(n, m);
     return writeCanvasToPng(this->getCanvas());
 }