Implement color filter as GrGLEffect

src/gpu/gl/GrGLProgramDesc.cpp

Index: src/gpu/gl/GrGLProgramDesc.cpp
diff --git a/src/gpu/gl/GrGLProgramDesc.cpp b/src/gpu/gl/GrGLProgramDesc.cpp
index 91ac266093daf2742b0a2cad706bd501d3ba0a1d..586fc3b77599d8a42118e9142c71888bbde524e4 100644
--- a/src/gpu/gl/GrGLProgramDesc.cpp
+++ b/src/gpu/gl/GrGLProgramDesc.cpp
@@ -66,7 +66,8 @@ void GrGLProgramDesc::Build(const GrDrawState& drawState,
 
     bool colorIsTransBlack = SkToBool(blendOpts & GrDrawState::kEmitTransBlack_BlendOptFlag);
     bool colorIsSolidWhite = (blendOpts & GrDrawState::kEmitCoverage_BlendOptFlag) ||
-                             (!requiresColorAttrib && 0xffffffff == drawState.getColor());
+                             (!requiresColorAttrib && 0xffffffff == drawState.getColor()) ||
+                             drawState.numColorStages() > 0 && !(*drawState.getColorStage(0)->getEffect())->getWillUseInputColor();
 
     int numEffects = (skipColor ? 0 : drawState.numColorStages()) +
                      (skipCoverage ? 0 : drawState.numCoverageStages());
@@ -103,7 +104,6 @@ void GrGLProgramDesc::Build(const GrDrawState& drawState,
     }
 
     header->fEmitsPointSize = isPoints;
-    header->fColorFilterXfermode = skipColor ? SkXfermode::kDst_Mode : drawState.getColorFilterMode();
 
     // Currently the experimental GS will only work with triangle prims (and it doesn't do anything
     // other than pass through values from the VS to the FS anyway).
@@ -191,9 +191,10 @@ void GrGLProgramDesc::Build(const GrDrawState& drawState,
     if (!drawState.isCoverageDrawing() && !skipCoverage &&
         (drawState.numCoverageStages() > 0 || requiresCoverageAttrib)) {
         // color filter is applied between color/coverage computation
-        if (SkXfermode::kDst_Mode != header->fColorFilterXfermode) {
+        // TODO:
+        //if (SkXfermode::kDst_Mode != header->fColorFilterXfermode) {
             separateCoverageFromColor = true;
-        }
+            //}
 
         // If we're stenciling then we want to discard samples that have zero coverage
         if (drawState.getStencil().doesWrite()) {