non-linear blending first steps

Code:
  - Add a non-linear blending bit and makeNonlinearBlending()
    to SkColorSpace
  - remove enough F16=linear checks to make it possible to
    create surfaces and encode pngs with nonlinear F16

Testing:
  - add "esrgb" software config to DM, run it
  - add "srgbnl" software config, run it
  - deemphasize importance of "srgb" config on bots
  - update unit tests to reflect relaxed F16 constraints
  - add a new unit test file with _really_ basic tests,
    and a new unit test that's not working yet

Bug: skia:7942

Change-Id: I8ac042bdf9f3d791765393b68fd9256375184d83
Reviewed-on: https://skia-review.googlesource.com/127325
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Mike Klein <mtklein@chromium.org>

2 files changed, 2 insertions, 5 deletions

diff --git a/src/image/SkSurface_Gpu.cpp b/src/image/SkSurface_Gpu.cpp
index b646f9e506..d86b316ef6 100644
--- a/src/image/SkSurface_Gpu.cpp
+++ b/src/image/SkSurface_Gpu.cpp
@@ -271,7 +271,7 @@ bool SkSurface_Gpu::onDraw(const SkDeferredDisplayList* ddl) {
 bool SkSurface_Gpu::Valid(const SkImageInfo& info) {
     switch (info.colorType()) {
         case kRGBA_F16_SkColorType:
-            return (!info.colorSpace()) || info.colorSpace()->gammaIsLinear();
+            return true;
         case kRGBA_8888_SkColorType:
         case kBGRA_8888_SkColorType:
             return !info.colorSpace() || info.colorSpace()->gammaCloseToSRGB();
@@ -283,7 +283,7 @@ bool SkSurface_Gpu::Valid(const SkImageInfo& info) {
 bool SkSurface_Gpu::Valid(const GrCaps* caps, GrPixelConfig config, SkColorSpace* colorSpace) {
     switch (config) {
         case kRGBA_half_GrPixelConfig:
-            return (!colorSpace) || colorSpace->gammaIsLinear();
+            return true;
         case kSRGBA_8888_GrPixelConfig:
         case kSBGRA_8888_GrPixelConfig:
             return caps->srgbSupport() && colorSpace && colorSpace->gammaCloseToSRGB();
diff --git a/src/image/SkSurface_Raster.cpp b/src/image/SkSurface_Raster.cpp
index 47d5542ac6..fd120072f4 100644
--- a/src/image/SkSurface_Raster.cpp
+++ b/src/image/SkSurface_Raster.cpp
@@ -68,9 +68,6 @@ bool SkSurfaceValidateRasterInfo(const SkImageInfo& info, size_t rowBytes) {
             }
             break;
         case kRGBA_F16_SkColorType:
-            if (info.colorSpace() && (!info.colorSpace()->gammaIsLinear())) {
-                return false;
-            }
             break;
         default:
             return false;