color: Don't use QCMS for transforms unless necessary

ui/gfx/color_space.h

Index: ui/gfx/color_space.h
diff --git a/ui/gfx/color_space.h b/ui/gfx/color_space.h
index 798b9305a19b28d5941eae06812167aa77fd23ae..84b5e23546523449884f16c8e5a1da356814e478 100644
--- a/ui/gfx/color_space.h
+++ b/ui/gfx/color_space.h
@@ -178,6 +178,11 @@ class GFX_EXPORT ColorSpace {
   // range, and unspecified spaces.
   sk_sp<SkColorSpace> ToSkColorSpace() const;
 
+  // Populate |icc_profile| with an ICC profile that represents this color
+  // space. Returns false if this space is not representable. This ICC profile
+  // will be constructed ignoring the range adjust and transfer matrices.

[hubbe, 2017/02/16 01:28:29]

Ouch, if we can't represent those, shouldn't we just fail?

[ccameron, 2017/02/16 01:58:47]

This is written with the IOSurface API in mind -- in that API, you specify the
ICC profile of the transfer function and primaries that you want applied
(AFAICT).

[hubbe, 2017/02/16 08:33:02]

Can we add that to comment in the code, it doesn't make sense otherwise.

[ccameron, 2017/02/16 22:33:10]

Good point -- done.

+  bool GetICCProfile(ICCProfile* icc_profile) const;
+
   void GetPrimaryMatrix(SkMatrix44* to_XYZD50) const;
   bool GetTransferFunction(SkColorSpaceTransferFn* fn) const;
   bool GetInverseTransferFunction(SkColorSpaceTransferFn* fn) const;