GM: replace boilerplate with macros

gm/astcbitmap.cpp

Index: gm/astcbitmap.cpp
diff --git a/gm/astcbitmap.cpp b/gm/astcbitmap.cpp
index bc5e1e978f3027ce396beaac9c38b7879cad0842..d3191e25cca5f331b6b4fbc7d14053c4fb8f8dc2 100644
--- a/gm/astcbitmap.cpp
+++ b/gm/astcbitmap.cpp
@@ -42,26 +42,12 @@ static inline const char *get_astc_filename(int idx) {
     return kASTCFilenames[idx];
 }
 
-namespace skiagm {
+namespace {
+const int kGMDimension = 600;
+const int kBitmapDimension = kGMDimension / 4;
+}  // namespace
 
-/**
- *  Test decoding an image from an ASTC file and then from compressed ASTC data.
- */
-class ASTCBitmapGM : public GM {
-public:
-    ASTCBitmapGM() { }
-    virtual ~ASTCBitmapGM() { }
-
-protected:
-    SkString onShortName() override {
-        return SkString("astcbitmap");
-    }
-
-    SkISize onISize() override {
-        return SkISize::Make(kGMDimension, kGMDimension);
-    }
-
-    void onDraw(SkCanvas* canvas) override {
+DEF_SIMPLE_GM(astcbitmap, canvas, kGMDimension, kGMDimension) {
         for (int j = 0; j < 4; ++j) {
             for (int i = 0; i < 4; ++i) {
                 SkString filename = GetResourcePath(get_astc_filename(j*4+i));
@@ -86,17 +72,4 @@ protected:
                 canvas->drawBitmap(bm, bmX, bmY);
             }
         }
-    }
-
-private:
-    static const int kGMDimension = 600;
-    static const int kBitmapDimension = kGMDimension/4;
-
-    typedef GM INHERITED;
-};
-
-}  // namespace skiagm
-
-//////////////////////////////////////////////////////////////////////////////
-
-DEF_GM(return new skiagm::ASTCBitmapGM;)
+}