Use texture barriers to read directly from the RT

src/gpu/GrInOrderDrawBuffer.cpp

Index: src/gpu/GrInOrderDrawBuffer.cpp
diff --git a/src/gpu/GrInOrderDrawBuffer.cpp b/src/gpu/GrInOrderDrawBuffer.cpp
index 8289f006d41804ab5cdadd68c2d93a881aff5f72..643b2183d531f46df83e7ac0b8d070e7cc7a8428 100644
--- a/src/gpu/GrInOrderDrawBuffer.cpp
+++ b/src/gpu/GrInOrderDrawBuffer.cpp
@@ -393,6 +393,11 @@ bool GrInOrderDrawBuffer::onCopySurface(GrSurface* dst,
     return SkToBool(cmd);
 }
 
+void GrInOrderDrawBuffer::onBlendBarrier() {
+    GrTargetCommands::Cmd* cmd = fCommands.recordBlendBarrier(this);
+    this->recordTraceMarkersIfNecessary(cmd);
+}
+
 void GrInOrderDrawBuffer::recordTraceMarkersIfNecessary(GrTargetCommands::Cmd* cmd) {
     if (!cmd) {
         return;