SkColorCubeFilter: require alpha == 0xFF.

include/effects/SkColorCubeFilter.h

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkColorCubeFilter_DEFINED
 #define SkColorCubeFilter_DEFINED
 
 #include "SkColorFilter.h"
 #include "SkData.h"
 #include "SkMutex.h"
 
 class SK_API SkColorCubeFilter : public SkColorFilter {
 public:
     /** cubeData must containt a 3D data in the form of cube of the size:
      *  cubeDimension * cubeDimension * cubeDimension * sizeof(SkColor)
      *  This cube contains a transform where (x,y,z) maps to the (r,g,b).
-     *  The alpha components of the colors are ignored (treated as 0xFF).
+     *  The alpha components of the colors must be 0xFF.
      */

[Noel Gordon, 2015/08/20 01:43:29]

Yeap,
https://code.google.com/p/chromium/codesearch#chromium/src/third_party/qcms/s...
1222

     static SkColorFilter* Create(SkData* cubeData, int cubeDimension);
 
     void filterSpan(const SkPMColor src[], int count, SkPMColor[]) const override;
     uint32_t getFlags() const override;
 
 #if SK_SUPPORT_GPU
    bool asFragmentProcessors(GrContext*, GrProcessorDataManager*,
                              SkTDArray<GrFragmentProcessor*>*) const override;
 #endif
 
@@ skipping 37 matching lines @@
 
     SkAutoDataUnref fCubeData;
     int32_t fUniqueID;
 
     mutable ColorCubeProcesingCache fCache;
 
     typedef SkColorFilter INHERITED;
 };
 
 #endif