Refine constant sRGB and Adobe RGB to D50 matrices

The new values are calculated starting with the "true" values,
adapted to D50 using the Bradford transform.

I don't remember where the old values came from, they've been
around forever.  It's possible that I just typed in the values
that came out of ICC profiles (these would have been imperfect,
given that there's a fixed-point -> float conversion happening
there).

BUG=skia:

Change-Id: I8e870266bc8ab5372c3ccf6a5ee6691b2915af43
Reviewed-on: https://skia-review.googlesource.com/5450
Commit-Queue: Matt Sarett <msarett@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
diff --git a/src/core/SkColorSpace.cpp b/src/core/SkColorSpace.cpp
index e9db37a..54c85f1 100644
--- a/src/core/SkColorSpace.cpp
+++ b/src/core/SkColorSpace.cpp
@@ -87,6 +87,7 @@
     : fProfileData(std::move(profileData))
 {}
 
+#if defined(SK_USE_LEGACY_D50_MATRICES)
 static constexpr float gSRGB_toXYZD50[] {
     0.4358f, 0.3853f, 0.1430f,    // Rx, Gx, Bx
     0.2224f, 0.7170f, 0.0606f,    // Ry, Gy, Gz
@@ -98,6 +99,19 @@
     0.3111f, 0.6257f, 0.0632f,    // Ry, Gy, By
     0.0195f, 0.0609f, 0.7448f,    // Rz, Gz, Bz
 };
+#else
+static constexpr float gSRGB_toXYZD50[] {
+    0.4360747f, 0.3850649f, 0.1430804f, // Rx, Gx, Bx
+    0.2225045f, 0.7168786f, 0.0606169f, // Ry, Gy, Gz
+    0.0139322f, 0.0971045f, 0.7141733f, // Rz, Gz, Bz
+};
+
+static constexpr float gAdobeRGB_toXYZD50[] {
+    0.6097559f, 0.2052401f, 0.1492240f, // Rx, Gx, Bx
+    0.3111242f, 0.6256560f, 0.0632197f, // Ry, Gy, Gz
+    0.0194811f, 0.0608902f, 0.7448387f, // Rz, Gz, Bz
+};
+#endif
 
 /**
  *  Checks if our toXYZ matrix is a close match to a known color gamut.