Make existing unit tests only run on GL contexts

tests/ReadPixelsTest.cpp

Index: tests/ReadPixelsTest.cpp
diff --git a/tests/ReadPixelsTest.cpp b/tests/ReadPixelsTest.cpp
index 830dbb2861672eff5914607eff6ed4724d26f105..9db507b981dcb8bdd5329a52f6ccd0e19ffcd7ab 100644
--- a/tests/ReadPixelsTest.cpp
+++ b/tests/ReadPixelsTest.cpp
@@ -387,7 +387,7 @@ DEF_TEST(ReadPixels, reporter) {
     test_readpixels(reporter, surface, kLastAligned_BitmapInit);
 }
 #if SK_SUPPORT_GPU
-DEF_GPUTEST_FOR_RENDERING_CONTEXTS(ReadPixels_Gpu, reporter, ctxInfo) {
+DEF_GPUTEST_FOR_GL_RENDERING_CONTEXTS(ReadPixels_Gpu, reporter, ctxInfo) {
     for (auto& origin : {kBottomLeft_GrSurfaceOrigin, kTopLeft_GrSurfaceOrigin}) {
         GrSurfaceDesc desc;
         desc.fFlags = kRenderTarget_GrSurfaceFlag;
@@ -442,7 +442,7 @@ static void test_readpixels_texture(skiatest::Reporter* reporter, GrTexture* tex
         }
     }
 }
-DEF_GPUTEST_FOR_RENDERING_CONTEXTS(ReadPixels_Texture, reporter, ctxInfo) {
+DEF_GPUTEST_FOR_GL_RENDERING_CONTEXTS(ReadPixels_Texture, reporter, ctxInfo) {
     // On the GPU we will also try reading back from a non-renderable texture.
     for (auto& origin : {kBottomLeft_GrSurfaceOrigin, kTopLeft_GrSurfaceOrigin}) {
         SkAutoTUnref<GrTexture> texture;
@@ -576,7 +576,7 @@ static void dump_to_file(const char name[], SkData* data) {
  *
  *  https://bug.skia.org/4351
  */
-DEF_GPUTEST_FOR_RENDERING_CONTEXTS(ReadPixels_Subset_Gpu, reporter, ctxInfo) {
+DEF_GPUTEST_FOR_GL_RENDERING_CONTEXTS(ReadPixels_Subset_Gpu, reporter, ctxInfo) {
     SkBitmap bitmap;
     make_ringed_bitmap(&bitmap, 6, 6);
     const SkIRect subset = SkIRect::MakeLTRB(2, 2, 4, 4);