Revert "Move DstCopy on gpu into the GrXferProcessor."

This reverts commit 74a11753604768bf461b80cabb66060e8564d82c.

TBR=joshualitt@google.com,bsalomon@google.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=skia:

Committed: https://skia.googlesource.com/skia/+/3e9dfdb3784c0cbfecf7589a74aa9aff7ef40abd

Review URL: https://codereview.chromium.org/896163003
diff --git a/src/gpu/GrPipelineBuilder.cpp b/src/gpu/GrPipelineBuilder.cpp
index 54d357f..90aee74 100644
--- a/src/gpu/GrPipelineBuilder.cpp
+++ b/src/gpu/GrPipelineBuilder.cpp
@@ -101,8 +101,8 @@
 
 //////////////////////////////////////////////////////////////////////////////s
 
-bool GrPipelineBuilder::willXPNeedDstCopy(const GrDrawTargetCaps& caps) const {
-    return this->getXPFactory()->willNeedDstCopy(caps);
+bool GrPipelineBuilder::willEffectReadDstColor() const {
+    return this->getXPFactory()->willReadDst();
 }
 
 void GrPipelineBuilder::AutoRestoreEffects::set(GrPipelineBuilder* pipelineBuilder) {