Fix some bugs and performance issues with skiaserve

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1777203003

Review URL: https://codereview.chromium.org/1777203003
diff --git a/tools/skiaserve/Request.h b/tools/skiaserve/Request.h
index 0a2b17a..95e7f15 100644
--- a/tools/skiaserve/Request.h
+++ b/tools/skiaserve/Request.h
@@ -61,8 +61,8 @@
     void drawToCanvas(int n, int m = -1);
     SkSurface* createCPUSurface();
     SkSurface* createGPUSurface();
-    GrAuditTrail* getAuditTrail(SkCanvas*);
-    void cleanupAuditTrail(SkCanvas*);
+    SkIRect getBounds();
+    GrContext* getContext();
     
     SkAutoTUnref<SkPicture> fPicture;
     SkAutoTDelete<GrContextFactory> fContextFactory;