switch to alternate SkColorSpace::toXYZD50()

Both SkColorSpace::toXYZD50() routines return the same information, but
the out-parameter version gives more flexibility in how SkColorSpace
represents that gamut matrix internally.  As is, there's no way around
storing an SkMatrix44.

Change-Id: I8459f4e611890114bace574df098040441e698f8
Reviewed-on: https://chromium-review.googlesource.com/c/1261397Reviewed-by: ccameron <ccameron@chromium.org>
Commit-Queue: Mike Klein <mtklein@chromium.org>
Cr-Commit-Position: refs/heads/master@{#596745}

ui/gfx/color_space.cc

@@ -120,9 +120,10 @@ ColorSpace::ColorSpace(const SkColorSpace& sk_color_space)
   }
 
   // Use custom primaries, if they are representable as a "to XYZD50" matrix.
-  if (const auto* to_XYZD50 = sk_color_space.toXYZD50()) {
+  SkMatrix44 to_XYZD50{SkMatrix44::kUninitialized_Constructor};
+  if (sk_color_space.toXYZD50(&to_XYZD50)) {
     primaries_ = PrimaryID::CUSTOM;
-    SetCustomPrimaries(*to_XYZD50);
+    SetCustomPrimaries(to_XYZD50);
     return;
   }