Add xp optimization for RGB coverage.

src/gpu/GrOptDrawState.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrOptDrawState.h"
 
 #include "GrDrawState.h"
@@ skipping 139 matching lines @@
 
 void GrOptDrawState::adjustProgramFromOptimizations(const GrDrawState& ds,
                                                     GrXferProcessor::OptFlags flags,
                                                     const GrProcOptInfo& colorPOI,
                                                     const GrProcOptInfo& coveragePOI,
                                                     int* firstColorStageIdx,
                                                     int* firstCoverageStageIdx) {
     fDescInfo.fReadsDst = false;
     fDescInfo.fReadsFragPosition = false;
 
-    if (flags & GrXferProcessor::kClearColorStages_OptFlag) {
+    if (flags & GrXferProcessor::kClearColorStages_OptFlag ||
+        flags & GrXferProcessor::kOverrideColor_OptFlag) {
         fDescInfo.fInputColorIsUsed = true;
         *firstColorStageIdx = ds.numColorStages();
         fDescInfo.fHasVertexColor = false;
     } else {
         fDescInfo.fReadsDst = colorPOI.readsDst();
         fDescInfo.fReadsFragPosition = colorPOI.readsFragPosition();
     }
 
     if (flags & GrXferProcessor::kClearCoverageStages_OptFlag) {
         fDescInfo.fInputCoverageIsUsed = true;
@@ skipping 60 matching lines @@
     SkASSERT(this->numFragmentStages() == that.numFragmentStages());
     for (int i = 0; i < this->numFragmentStages(); i++) {
 
         if (this->getFragmentStage(i) != that.getFragmentStage(i)) {
             return false;
         }
     }
     return true;
 }