Use new skia isPQish and isHLGish functions where applicable.

PaintImage::GetContentColorUsage() and gfx::ColorSpace construction
both use ad hoc methods for determining if the transfer function is
PQ or HLG, instead use the new sanctioned Skia methods.

R=ccameron

Fixed: 1106417e
Change-Id: Ia515c60d92d1733e4edfba369071050dd6805ccc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2311123
Commit-Queue: Dale Curtis <dalecurtis@chromium.org>
Commit-Queue: ccameron <ccameron@chromium.org>
Reviewed-by: ccameron <ccameron@chromium.org>
Auto-Submit: Dale Curtis <dalecurtis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#790644}

cc/paint/BUILD.gn

@@ -100,6 +100,7 @@ cc_component("paint") {
     "//cc/base",
     "//cc/debug",
     "//skia",
+    "//skia:skcms",
     "//ui/gfx:color_space",
     "//ui/gfx:geometry_skia",
     "//ui/gfx/geometry",

cc/paint/paint_image.cc

@@ -293,10 +293,12 @@ gfx::ContentColorUsage PaintImage::GetContentColorUsage() const {
   if (!color_space || color_space->isSRGB())
     return gfx::ContentColorUsage::kSRGB;
 
-  // TODO(crbug.com/1106417): Use SkColorSpace::isHDR() when available.
   skcms_TransferFunction fn;
-  if (!color_space->isNumericalTransferFn(&fn) && fn.g < 0)
+  if (!color_space->isNumericalTransferFn(&fn) &&
+      (skcms_TransferFunction_isPQish(&fn) ||
+       skcms_TransferFunction_isHLGish(&fn))) {
     return gfx::ContentColorUsage::kHDR;
+  }
 
   // If it's not HDR and not SRGB, report it as WCG.
   return gfx::ContentColorUsage::kWideColorGamut;

ui/gfx/color_space.cc

@@ -97,19 +97,13 @@ ColorSpace::ColorSpace(const SkColorSpace& sk_color_space)
                  TransferID::INVALID,
                  MatrixID::RGB,
                  RangeID::FULL) {
-  // Special case the HDR transfer functions since they're not numerical
-  auto transfer_eq = [](skcms_TransferFunction x, skcms_TransferFunction y) {
-    return x.g == y.g && x.a == y.a && x.b == y.b && x.c == y.c && x.d == y.d &&
-           x.e == y.e && x.f == y.f;
-  };
-
   skcms_TransferFunction fn;
   if (sk_color_space.isNumericalTransferFn(&fn)) {
     transfer_ = TransferID::CUSTOM;
     SetCustomTransferFunction(fn);
-  } else if (transfer_eq(fn, SkNamedTransferFn::kHLG)) {
+  } else if (skcms_TransferFunction_isHLGish(&fn)) {
     transfer_ = TransferID::ARIB_STD_B67;
-  } else if (fn.g == SkNamedTransferFn::kPQ.g) {
+  } else if (skcms_TransferFunction_isPQish(&fn)) {
     transfer_ = TransferID::SMPTEST2084;
     transfer_params_[0] = GetSDRWhiteLevelFromPQSkTransferFunction(fn);
   } else {