Use texture barriers to read directly from the RT
Updates GrXferProcessor to read directly from the RT texture when
texture barriers are supported and it needs to know the dst color.
Also adds the notion of an Xfer barrier and uses it to issue texture
barriers when the XP will read the RT.
BUG=skia:
Review URL: https://codereview.chromium.org/1040303002
diff --git a/src/gpu/GrTest.cpp b/src/gpu/GrTest.cpp
index 3c5d3dd..23739f2 100644
--- a/src/gpu/GrTest.cpp
+++ b/src/gpu/GrTest.cpp
@@ -170,6 +170,8 @@
return false;
}
+ void xferBarrier(GrXferBarrierType) override {}
+
private:
void onResetContext(uint32_t resetBits) override {}