GM: replace boilerplate with macros

gm/bigmatrix.cpp

Index: gm/bigmatrix.cpp
diff --git a/gm/bigmatrix.cpp b/gm/bigmatrix.cpp
index c7c3b0dd07ea4855c9bf9ef12f833fdd3d0f2ddc..2d2b7d9f7ee95a53f08c58a8b36f81db175b8293 100644
--- a/gm/bigmatrix.cpp
+++ b/gm/bigmatrix.cpp
@@ -11,24 +11,8 @@
 #include "SkPath.h"
 #include "SkShader.h"
 
-namespace skiagm {
-
-class BigMatrixGM : public GM {
-public:
-    BigMatrixGM() {
-        this->setBGColor(sk_tool_utils::color_to_565(0xFF66AA99));
-    }
-
-protected:
-    virtual SkString onShortName() {
-        return SkString("bigmatrix");
-    }
-
-    virtual SkISize onISize() {
-        return SkISize::Make(50, 50);
-    }
-
-    virtual void onDraw(SkCanvas* canvas) {
+DEF_SIMPLE_GM_BG(bigmatrix, canvas, 50, 50,
+                 sk_tool_utils::color_to_565(0xFF66AA99)) {
         SkMatrix m;
         m.reset();
         m.setRotate(33 * SK_Scalar1);
@@ -82,15 +66,4 @@ protected:
         rect.setLTRB(pt.fX - small, pt.fY - small,
                      pt.fX + small, pt.fY + small);
         canvas->drawRect(rect, paint);
-    }
-
-private:
-    typedef GM INHERITED;
-};
-
-//////////////////////////////////////////////////////////////////////////////
-
-static GM* MyFactory(void*) { return new BigMatrixGM; }
-static GMRegistry reg(MyFactory);
-
 }