Replace a lot of 'static const' with 'constexpr' or 'const'.

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 144 matching lines @@
                               gModes[i].fMode, nullptr, nullptr);
             canvas->translate(0.0f, numColors*(target.height()+kPad));
             // w a paint
             canvas->drawAtlas(fAtlas.get(), xforms, rects, quadColors, numColors,
                               gModes[i].fMode, nullptr, &paint);
             canvas->restore();
         }
     }
 
 private:
-    static const int kNumXferModes = 29;
-    static const int kNumColors = 4;
-    static const int kAtlasSize = 30;
-    static const int kPad = 2;
-    static const int kTextPad = 8;
+    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; )