Remove canApplyCoverage from XP and all related functions in gpu code.

include/gpu/GrXferProcessor.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 GrXferProcessor_DEFINED
 #define GrXferProcessor_DEFINED
 
@@ skipping 214 matching lines @@
                                          const GrDeviceCoordTexture* dstCopy,
                                          const GrDrawTargetCaps& caps) const;
 
     /**
      * This function returns true if the GrXferProcessor generated from this factory will be able to
      * correctly blend when using RGB coverage. The knownColor and knownColorFlags represent the
      * final computed color from the color stages.
      */
     virtual bool supportsRGBCoverage(GrColor knownColor, uint32_t knownColorFlags) const = 0;
 
-    /**
-     * Depending on color blend mode requested it may or may not be possible to correctly blend with
-     * fractional pixel coverage generated by the fragment shader.
-     *
-     * This function considers the known color and coverage input into the xfer processor and
-     * certain state information (colorWriteDisabled) to determine whether
-     * coverage can be handled correctly.
-     */
-    virtual bool canApplyCoverage(const GrProcOptInfo& colorPOI,
-                                  const GrProcOptInfo& coveragePOI) const = 0;
-
-
     struct InvariantOutput {
         bool        fWillBlendWithDst;
         GrColor     fBlendedColor;
         uint32_t    fBlendedColorFlags;
     };
 
     /** 
      * This function returns known information about the output of the xfer processor produced by
      * this xp factory. The invariant color information returned by this function refers to the
      * final color produced after all blending.
@@ skipping 65 matching lines @@
     enum {
         kIllegalXPFClassID = 0,
     };
     static int32_t gCurrXPFClassID;
 
     typedef GrProgramElement INHERITED;
 };
 
 #endif