Set willReadFragmentPosition on XP when doing a DstCopy.

src/gpu/GrXferProcessor.cpp

Index: src/gpu/GrXferProcessor.cpp
diff --git a/src/gpu/GrXferProcessor.cpp b/src/gpu/GrXferProcessor.cpp
index 358a24906092cb6bf6d034b474be27694d23364d..476394f8009ae208a459e01415b5b746295a65ff 100644
--- a/src/gpu/GrXferProcessor.cpp
+++ b/src/gpu/GrXferProcessor.cpp
@@ -18,6 +18,7 @@ GrXferProcessor::GrXferProcessor(const GrDeviceCoordTexture* dstCopy, bool willR
         fDstCopy.reset(dstCopy->texture());
         fDstCopyTextureOffset = dstCopy->offset();
         this->addTextureAccess(&fDstCopy);

[robertphillips, 2015/04/07 14:12:58]

So we always read the frag position?

[egdaniel, 2015/04/07 14:18:11]

if we have made an actual dstCopy then we will always read it.

[bsalomon, 2015/04/07 14:18:40]

If we're reading a dst copy, we use the fragment position as texture coords.

lgtm

+        this->setWillReadFragmentPosition();
     }
 }