Implement support for dual source blending in ES

src/gpu/gl/builders/GrGLFragmentShaderBuilder.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 GrGLFragmentShaderBuilder_DEFINED
 #define GrGLFragmentShaderBuilder_DEFINED
 
@@ skipping 113 matching lines @@
      * An internal call for GrGLProgramBuilder to use to add varyings to the vertex shader
      */
     void addVarying(GrGLVarying*, GrSLPrecision);
 
     /**
      * Features that should only be enabled by GrGLFragmentShaderBuilder itself.
      */
     enum GLSLPrivateFeature {
         kFragCoordConventions_GLSLPrivateFeature = kLastGLSLFeature + 1,
         kBlendEquationAdvanced_GLSLPrivateFeature,
-        kLastGLSLPrivateFeature = kBlendEquationAdvanced_GLSLPrivateFeature
+        kBlendFuncExtended_GLSLPrivateFeature,
+        kLastGLSLPrivateFeature = kBlendFuncExtended_GLSLPrivateFeature
     };
 
     // Interpretation of DstReadKey when generating code
     enum {
         kNoDstRead_DstReadKey           = 0,
         kYesDstRead_DstReadKeyBit       = 0x1, // Set if we do a dst-copy-read.
         kUseAlphaConfig_DstReadKeyBit   = 0x2, // Set if dst-copy config is alpha only.
         kTopLeftOrigin_DstReadKeyBit    = 0x4, // Set if dst-copy origin is top-left.
     };
 
@@ skipping 16 matching lines @@
     // the program creator
     bool fHasReadDstColor;
     bool fHasReadFragmentPosition;
 
     friend class GrGLProgramBuilder;
 
     typedef GrGLXPFragmentBuilder INHERITED;
 };
 
 #endif