Apply SDR white level scaling to YUV quads in Skia renderer

This is the same strategy used by gl_renderer. It's potentially expensive,
because the transform matrix values are baked into the shader source, so
dragging the slider could cause many shaders to be generated.

A better solution might be to inject a scale step in the ColorTransform
that refers to a uniform. Doing so would require changing the signature
of NewColorTransform (or adding NewScaledColorTransform), and creates a
leaky abstraction that may not be worth it, given the rarity of this case.

Bug: chromium:985500
Change-Id: Ifae5e595fa76c84b0535ae6ca222bf7bf088883f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1919419Reviewed-by: kylechar <kylechar@chromium.org>
Commit-Queue: Brian Osman <brianosman@google.com>
Cr-Commit-Position: refs/heads/master@{#715812}

components/viz/service/display/skia_renderer.cc

@@ -2096,12 +2096,20 @@ sk_sp<SkColorFilter> SkiaRenderer::GetColorFilter(const gfx::ColorSpace& src,
                                                   const gfx::ColorSpace& dst,
                                                   float resource_offset,
                                                   float resource_multiplier) {
+  gfx::ColorSpace adjusted_src = src;
+  float sdr_white_level = current_frame()->sdr_white_level;
+  if (src.IsValid() && !src.IsHDR() &&
+      sdr_white_level != gfx::ColorSpace::kDefaultSDRWhiteLevel) {
+    adjusted_src = src.GetScaledColorSpace(
+        sdr_white_level / gfx::ColorSpace::kDefaultSDRWhiteLevel);
+  }
+
   std::unique_ptr<SkRuntimeColorFilterFactory>& factory =
-      color_filter_cache_[dst][src];
+      color_filter_cache_[dst][adjusted_src];
   if (!factory) {
     std::unique_ptr<gfx::ColorTransform> transform =
         gfx::ColorTransform::NewColorTransform(
-            src, dst, gfx::ColorTransform::Intent::INTENT_PERCEPTUAL);
+            adjusted_src, dst, gfx::ColorTransform::Intent::INTENT_PERCEPTUAL);
     // TODO(backer): Support lookup table transforms (e.g.
     // COLOR_CONVERSION_MODE_LUT).
     if (!transform->CanGetShaderSource())