color: Add support for shader generation

ui/gfx/color_transform.h

 // Copyright (c) 2016 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_TRANSFORM_H_
 #define UI_GFX_COLOR_TRANSFORM_H_
 
 #include "base/macros.h"
 #include "ui/gfx/color_space.h"
 #include "ui/gfx/geometry/point3_f.h"
 #include "ui/gfx/gfx_export.h"
 
 namespace gfx {
 
 class GFX_EXPORT ColorTransform {
  public:
   enum class Intent { INTENT_ABSOLUTE, INTENT_PERCEPTUAL, TEST_NO_OPT };
 
   // TriStimulus is a color coordinate in any color space.
   // Channel order is XYZ, RGB or YUV.
   typedef Point3F TriStim;
 
   ColorTransform();
   virtual ~ColorTransform();
+  virtual gfx::ColorSpace GetSrcColorSpace() const = 0;
+  virtual gfx::ColorSpace GetDstColorSpace() const = 0;
 
   // Perform transformation of colors, |colors| is both input and output.
-  virtual void Transform(TriStim* colors, size_t num) = 0;
+  virtual void Transform(TriStim* colors, size_t num) const = 0;
+
+  // Return GLSL shader source that defines a function DoColorConversion that
+  // converts a vec3 according to this transform.
+  virtual bool CanGetShaderSource() const = 0;
+  virtual std::string GetShaderSource() const = 0;
+
+  // Returns true if this transform is the identity.
+  virtual bool IsIdentity() const = 0;
 
   virtual size_t NumberOfStepsForTesting() const = 0;
 
   static std::unique_ptr<ColorTransform> NewColorTransform(
       const ColorSpace& from,
       const ColorSpace& to,
       Intent intent);
 
  private:
   DISALLOW_COPY_AND_ASSIGN(ColorTransform);
 };
 
 }  // namespace gfx
 
 #endif  // UI_GFX_COLOR_TRANSFORM_H_