color: Don't use QCMS for transforms unless necessary

ui/gfx/color_space.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_GFX_COLOR_SPACE_H_
 #define UI_GFX_COLOR_SPACE_H_
 
 #include <stdint.h>
 
 #include "base/gtest_prod_util.h"
@@ skipping 160 matching lines @@
   bool operator==(const ColorSpace& other) const;
   bool operator!=(const ColorSpace& other) const;
   bool operator<(const ColorSpace& other) const;
 
   bool IsHDR() const;
 
   // This will return nullptr for non-RGB spaces, spaces with non-FULL
   // 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;
 
   // For most formats, this is the RGB to YUV matrix.
   void GetTransferMatrix(SkMatrix44* matrix) const;
   void GetRangeAdjustMatrix(SkMatrix44* matrix) const;
 
  private:
   PrimaryID primaries_ = PrimaryID::UNSPECIFIED;
@@ skipping 18 matching lines @@
   friend class ColorTransform;
   friend class ColorTransformInternal;
   friend class ColorSpaceWin;
   friend struct IPC::ParamTraits<gfx::ColorSpace>;
   FRIEND_TEST_ALL_PREFIXES(SimpleColorSpace, GetColorSpace);
 };
 
 }  // namespace gfx
 
 #endif  // UI_GFX_COLOR_SPACE_H_