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

gm/gradient_matrix.cpp

Index: gm/gradient_matrix.cpp
diff --git a/gm/gradient_matrix.cpp b/gm/gradient_matrix.cpp
index 816891847ddf4a521898028a27b89c9349bc74a3..3992a49d44f9c037a593c518b08727ef85ba8700 100644
--- a/gm/gradient_matrix.cpp
+++ b/gm/gradient_matrix.cpp
@@ -19,19 +19,19 @@
 
 #include "gm.h"
 
-static const SkColor gColors[] = {
+constexpr SkColor gColors[] = {
     SK_ColorRED, SK_ColorYELLOW
 };
 
 // These annoying defines are necessary, because the only other alternative
 // is to use SkIntToScalar(...) everywhere.
-static const SkScalar sZero = 0;
-static const SkScalar sHalf = SK_ScalarHalf;
-static const SkScalar sOne = SK_Scalar1;
+constexpr SkScalar sZero = 0;
+constexpr SkScalar sHalf = SK_ScalarHalf;
+constexpr SkScalar sOne = SK_Scalar1;
 
 // These arrays define the gradient stop points
 // as x1, y1, x2, y2 per gradient to draw.
-static const SkPoint linearPts[][2] = {
+constexpr SkPoint linearPts[][2] = {
     {{sZero, sZero}, {sOne,  sZero}},
     {{sZero, sZero}, {sZero, sOne}},
     {{sOne,  sZero}, {sZero, sZero}},
@@ -43,7 +43,7 @@ static const SkPoint linearPts[][2] = {
     {{sZero, sOne},  {sOne,  sZero}}
 };
 
-static const SkPoint radialPts[][2] = {
+constexpr SkPoint radialPts[][2] = {
     {{sZero, sHalf}, {sOne,  sHalf}},
     {{sHalf, sZero}, {sHalf, sOne}},
     {{sOne,  sHalf}, {sZero, sHalf}},
@@ -56,10 +56,10 @@ static const SkPoint radialPts[][2] = {
 };
 
 // These define the pixels allocated to each gradient image.
-static const SkScalar TESTGRID_X = SkIntToScalar(200);
-static const SkScalar TESTGRID_Y = SkIntToScalar(200);
+constexpr SkScalar TESTGRID_X = SkIntToScalar(200);
+constexpr SkScalar TESTGRID_Y = SkIntToScalar(200);
 
-static const int IMAGES_X = 4;             // number of images per row
+constexpr int IMAGES_X = 4;             // number of images per row
 
 static sk_sp<SkShader> make_linear_gradient(const SkPoint pts[2], const SkMatrix& localMatrix) {
     return SkGradientShader::MakeLinear(pts, gColors, nullptr, SK_ARRAY_COUNT(gColors),