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

gm/bigtileimagefilter.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 "SkImageSource.h"
 #include "SkSurface.h"
 #include "SkTileImageFilter.h"
@@ skipping 76 matching lines @@
             SkRect bound3 = SkRect::MakeXYWH(320, 320,
                                              SkIntToScalar(kBitmapSize),
                                              SkIntToScalar(kBitmapSize));
             canvas->drawImageRect(fGreenImage.get(), bound2, bound3, nullptr,
                                   SkCanvas::kStrict_SrcRectConstraint);
             canvas->restore();
         }
     }
 
 private:
-    static const int kWidth = 512;
-    static const int kHeight = 512;
-    static const int kBitmapSize = 64;
+    static constexpr int kWidth = 512;
+    static constexpr int kHeight = 512;
+    static constexpr int kBitmapSize = 64;
 
     sk_sp<SkImage> fRedImage;
     sk_sp<SkImage> fGreenImage;
 
     typedef GM INHERITED;
 };
 
 //////////////////////////////////////////////////////////////////////////////
 
 DEF_GM(return new BigTileImageFilterGM;)
 }