Remove caching from the draw-atlas GMs. Fixes bugs cycling backends.

gm/drawatlascolor.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "gm.h"
 #include "SkCanvas.h"
 #include "SkRSXform.h"
@@ skipping 54 matching lines @@
     }
 
     SkISize onISize() override {
         return SkISize::Make(kNumXferModes * (kAtlasSize + kPad) + kPad,
                              2 * kNumColors * (kAtlasSize + kPad) + kTextPad + kPad);
     }
 
     void onDraw(SkCanvas* canvas) override {
         const SkRect target = SkRect::MakeWH(SkIntToScalar(kAtlasSize), SkIntToScalar(kAtlasSize));
 
-        if (nullptr == fAtlas) {
-            fAtlas = make_atlas(canvas, kAtlasSize);
-        }
+        auto atlas = make_atlas(canvas, kAtlasSize);
 
         const struct {
             SkXfermode::Mode fMode;
             const char*      fLabel;
         } gModes[] = {
             { SkXfermode::kClear_Mode,      "Clear"     },
             { SkXfermode::kSrc_Mode,        "Src"       },
             { SkXfermode::kDst_Mode,        "Dst"       },
             { SkXfermode::kSrcOver_Mode,    "SrcOver"   },
             { SkXfermode::kDstOver_Mode,    "DstOver"   },
@@ skipping 56 matching lines @@
             canvas->drawText(gModes[i].fLabel, strlen(gModes[i].fLabel),
                              i*(target.width()+kPad)+kPad, SkIntToScalar(kTextPad),
                              textP);
         }
 
         for (int i = 0; i < numModes; ++i) {
             canvas->save();
             canvas->translate(SkIntToScalar(i*(target.height()+kPad)),
                               SkIntToScalar(kTextPad+kPad));
             // w/o a paint
-            canvas->drawAtlas(fAtlas.get(), xforms, rects, quadColors, numColors,
+            canvas->drawAtlas(atlas.get(), xforms, rects, quadColors, numColors,
                               gModes[i].fMode, nullptr, nullptr);
             canvas->translate(0.0f, numColors*(target.height()+kPad));
             // w a paint
-            canvas->drawAtlas(fAtlas.get(), xforms, rects, quadColors, numColors,
+            canvas->drawAtlas(atlas.get(), xforms, rects, quadColors, numColors,
                               gModes[i].fMode, nullptr, &paint);
             canvas->restore();
         }
     }
 
 private:
     static constexpr int kNumXferModes = 29;
     static constexpr int kNumColors = 4;
     static constexpr int kAtlasSize = 30;
     static constexpr int kPad = 2;
     static constexpr int kTextPad = 8;
 
-
-    sk_sp<SkImage> fAtlas;
-
     typedef GM INHERITED;
 };
 DEF_GM( return new DrawAtlasColorsGM; )