Add GrColor4f type, store that in GrPaint. Linearize based on global flag.

src/gpu/GrPaint.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrPaint.h"
 
 #include "GrProcOptInfo.h"
 #include "effects/GrCoverageSetOpXP.h"
 #include "effects/GrPorterDuffXferProcessor.h"
 #include "effects/GrSimpleTextureEffect.h"
 
 GrPaint::GrPaint()
     : fAntiAlias(false)
     , fDisableOutputConversionToSRGB(false)
     , fAllowSRGBInputs(false)
-    , fColor(GrColor_WHITE) {}
+    , fColor(GrColor4f::FromGrColor(GrColor_WHITE)) {}
 
 void GrPaint::setCoverageSetOpXPFactory(SkRegion::Op regionOp, bool invertCoverage) {
     fXPFactory = GrCoverageSetOpXPFactory::Make(regionOp, invertCoverage);
 }
 
 void GrPaint::addColorTextureProcessor(GrTexture* texture, const SkMatrix& matrix) {
     this->addColorFragmentProcessor(GrSimpleTextureEffect::Make(texture, matrix));
 }
 
 void GrPaint::addCoverageTextureProcessor(GrTexture* texture, const SkMatrix& matrix) {
     this->addCoverageFragmentProcessor(GrSimpleTextureEffect::Make(texture, matrix));
 }
 
 void GrPaint::addColorTextureProcessor(GrTexture* texture,
                                        const SkMatrix& matrix,
                                        const GrTextureParams& params) {
     this->addColorFragmentProcessor(GrSimpleTextureEffect::Make(texture, matrix, params));
 }
 
 void GrPaint::addCoverageTextureProcessor(GrTexture* texture,
                                           const SkMatrix& matrix,
                                           const GrTextureParams& params) {
     this->addCoverageFragmentProcessor(GrSimpleTextureEffect::Make(texture, matrix, params));
 }
 
 bool GrPaint::isConstantBlendedColor(GrColor* color) const {
     GrProcOptInfo colorProcInfo;
     colorProcInfo.calcWithInitialValues(
         sk_sp_address_as_pointer_address(fColorFragmentProcessors.begin()),
-        this->numColorFragmentProcessors(), fColor, kRGBA_GrColorComponentFlags, false);
+        this->numColorFragmentProcessors(), this->getColor(), kRGBA_GrColorComponentFlags, false);
 
     GrXPFactory::InvariantBlendedColor blendedColor;
     if (fXPFactory) {
         fXPFactory->getInvariantBlendedColor(colorProcInfo, &blendedColor);
     } else {
         GrPorterDuffXPFactory::SrcOverInvariantBlendedColor(colorProcInfo.color(),
                                                             colorProcInfo.validFlags(),
                                                             colorProcInfo.isOpaque(),
                                                             &blendedColor);
     }
 
     if (kRGBA_GrColorComponentFlags == blendedColor.fKnownColorFlags) {
         *color = blendedColor.fKnownColor;
         return true;
     }
     return false;
 }