Require sRGB write control for sRGB support. Add flag to GrPaint to suppress linear -> sRGB convers…

include/gpu/GrPaint.h

Index: include/gpu/GrPaint.h
diff --git a/include/gpu/GrPaint.h b/include/gpu/GrPaint.h
index 152cb51d7e7144373e360abf0c611c92db453c91..3f06f092ab45fe55b132252f2d647356c0feefe8 100644
--- a/include/gpu/GrPaint.h
+++ b/include/gpu/GrPaint.h
@@ -56,6 +56,13 @@ public:
     void setAntiAlias(bool aa) { fAntiAlias = aa; }
     bool isAntiAlias() const { return fAntiAlias; }
 
+    /**
+     * Should shader output conversion from linear to sRGB be disabled.
+     * Only relevant if the destination is sRGB. Defaults to false.
+     */
+    void setDisableOutputConversionToSRGB(bool srgb) { fDisableOutputConversionToSRGB = srgb; }
+    bool getDisableOutputConversionToSRGB() const { return fDisableOutputConversionToSRGB; }
+
     const GrXPFactory* setXPFactory(const GrXPFactory* xpFactory) {
         fXPFactory.reset(SkSafeRef(xpFactory));
         return xpFactory;
@@ -112,6 +119,7 @@ public:
 
     GrPaint& operator=(const GrPaint& paint) {
         fAntiAlias = paint.fAntiAlias;
+        fDisableOutputConversionToSRGB = paint.fDisableOutputConversionToSRGB;
 
         fColor = paint.fColor;
         this->resetFragmentProcessors();
@@ -154,6 +162,7 @@ private:
     SkSTArray<2, const GrFragmentProcessor*, true>  fCoverageFragmentProcessors;
 
     bool                                            fAntiAlias;
+    bool                                            fDisableOutputConversionToSRGB;
 
     GrColor                                         fColor;
 };