viz: SkColor to uint32_t

The color here is not a real SkColor, use uint32_t instead.
This is a follow up for(Brian Salomon comments):
https://chromium-review.googlesource.com/c/chromium/src/+/1068649

BUG=821176

Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:win_optional_gpu_tests_rel
Change-Id: I69adc5cebffee772634186fc8d9438de8e3e8523
Reviewed-on: https://chromium-review.googlesource.com/1074831Reviewed-by: Brian Salomon <bsalomon@chromium.org>
Reviewed-by: weiliangc <weiliangc@chromium.org>
Commit-Queue: Xing Xu <xing.xu@intel.com>
Cr-Commit-Position: refs/heads/master@{#563114}

components/viz/service/display/renderer_pixeltest.cc

@@ -1281,28 +1281,28 @@ TYPED_TEST(IntersectingQuadPixelTest, SolidColorQuads) {
       FILE_PATH_LITERAL("intersecting_blue_green.png"));
 }
 
-static inline SkColor GetSkiaOrGLColor(const SkColor& color) {
+static inline uint32_t GetSkiaOrGLColor(const SkColor& color) {
   return SkColorSetARGB(SkColorGetA(color), SkColorGetB(color),
                         SkColorGetG(color), SkColorGetR(color));
 }
 
 template <typename TypeParam>
-SkColor GetColor(const SkColor& color) {
+uint32_t GetColor(const SkColor& color) {
   return color;
 }
 
 template <>
-SkColor GetColor<GLRenderer>(const SkColor& color) {
+uint32_t GetColor<GLRenderer>(const SkColor& color) {
   return GetSkiaOrGLColor(color);
 }
 
 template <>
-SkColor GetColor<SkiaRenderer>(const SkColor& color) {
+uint32_t GetColor<SkiaRenderer>(const SkColor& color) {
   return GetSkiaOrGLColor(color);
 }
 
 template <>
-SkColor GetColor<cc::GLRendererWithExpandedViewport>(const SkColor& color) {
+uint32_t GetColor<cc::GLRendererWithExpandedViewport>(const SkColor& color) {
   return GetSkiaOrGLColor(color);
 }