GM: replace boilerplate with macros

gm/imagefilters.cpp

Index: gm/imagefilters.cpp
diff --git a/gm/imagefilters.cpp b/gm/imagefilters.cpp
index e28bf5255ec754c95b95ac5c03a7d8dbb7b40623..8b4deca93a92f53e5380ef62192e572a3f293f90 100644
--- a/gm/imagefilters.cpp
+++ b/gm/imagefilters.cpp
@@ -16,15 +16,7 @@
  *
  *  see skbug.com/3741
  */
-class ImageFilterXfermodeTestGM : public skiagm::GM {
-protected:
-    SkString onShortName() override {
-        return SkString("imagefilters_xfermodes");
-    }
-
-    SkISize onISize() override { return SkISize::Make(480, 480); }
-
-    void doDraw(SkCanvas* canvas, SkXfermode::Mode mode, SkImageFilter* imf) {
+static void do_draw(SkCanvas* canvas, SkXfermode::Mode mode, SkImageFilter* imf) {
         SkAutoCanvasRestore acr(canvas, true);
         canvas->clipRect(SkRect::MakeWH(220, 220));
         
@@ -47,9 +39,9 @@ protected:
         paint.setImageFilter(imf);
         paint.setXfermodeMode(mode);
         canvas->drawOval(r1, paint);
-    }
+}
 
-    void onDraw(SkCanvas* canvas) override {
+DEF_SIMPLE_GM(imagefilters_xfermodes, canvas, 480, 480) {
         canvas->translate(10, 10);
 
         // just need an imagefilter to trigger the code-path (which creates a tmp layer)
@@ -62,17 +54,11 @@ protected:
         
         for (size_t i = 0; i < SK_ARRAY_COUNT(modes); ++i) {
             canvas->save();
-            this->doDraw(canvas, modes[i], nullptr);
+            do_draw(canvas, modes[i], nullptr);
             canvas->translate(240, 0);
-            this->doDraw(canvas, modes[i], imf);
+            do_draw(canvas, modes[i], imf);
             canvas->restore();
             
             canvas->translate(0, 240);
         }
-    }
-
-private:
-    typedef GM INHERITED;
-};
-DEF_GM( return new ImageFilterXfermodeTestGM; )
-
+}