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

gm/yuvtorgbeffect.cpp

Index: gm/yuvtorgbeffect.cpp
diff --git a/gm/yuvtorgbeffect.cpp b/gm/yuvtorgbeffect.cpp
index 0be30088c8fbb0452f4e91a869c27a946bac39c7..d064cf3cf4b7e11e697ae2f64eb37383e0e4569f 100644
--- a/gm/yuvtorgbeffect.cpp
+++ b/gm/yuvtorgbeffect.cpp
@@ -94,9 +94,9 @@ protected:
             return;
         }
 
-        static const SkScalar kDrawPad = 10.f;
-        static const SkScalar kTestPad = 10.f;
-        static const SkScalar kColorSpaceOffset = 36.f;
+        constexpr SkScalar kDrawPad = 10.f;
+        constexpr SkScalar kTestPad = 10.f;
+        constexpr SkScalar kColorSpaceOffset = 36.f;
         SkISize sizes[3] = {{YSIZE, YSIZE}, {USIZE, USIZE}, {VSIZE, VSIZE}};
 
         for (int space = kJPEG_SkYUVColorSpace; space <= kLastEnum_SkYUVColorSpace;
@@ -211,9 +211,9 @@ protected:
             return;
         }
 
-        static const SkScalar kDrawPad = 10.f;
-        static const SkScalar kTestPad = 10.f;
-        static const SkScalar kColorSpaceOffset = 36.f;
+        constexpr SkScalar kDrawPad = 10.f;
+        constexpr SkScalar kTestPad = 10.f;
+        constexpr SkScalar kColorSpaceOffset = 36.f;
         SkISize sizes[3] = {{YSIZE, YSIZE}, {USIZE, USIZE}, {VSIZE, VSIZE}};
 
         for (int space = kJPEG_SkYUVColorSpace; space <= kLastEnum_SkYUVColorSpace; ++space) {