Replace fWillReadFragmentPosition with a bitfield

src/gpu/GrPipeline.cpp

Index: src/gpu/GrPipeline.cpp
diff --git a/src/gpu/GrPipeline.cpp b/src/gpu/GrPipeline.cpp
index e1c733a676114dd559795fcaee1eb7b19181221e..10905d003e22e9f9d9e606511fae71b957d72a5e 100644
--- a/src/gpu/GrPipeline.cpp
+++ b/src/gpu/GrPipeline.cpp
@@ -184,23 +184,19 @@ void GrPipeline::adjustProgramFromOptimizations(const GrPipelineBuilder& pipelin
                                                 int* firstColorProcessorIdx,
                                                 int* firstCoverageProcessorIdx) {
     fIgnoresCoverage = SkToBool(flags & GrXferProcessor::kIgnoreCoverage_OptFlag);
-    fReadsFragPosition = this->getXferProcessor().willReadFragmentPosition();
+    fBuiltInState = GrProcessor::kNone_BuiltInState;

[Chris Dalton, 2016/02/25 20:38:37]

We a problem here that fBuiltInState *should* intitialize with:

 fBuiltInState = GrPrimitiveProcessor.builtInState();

But I don't think the primitive processor is known yet at this point. Thoughts?
Otherwise if the primitive processor enables built in state, the pipeline won't
know about it.

[joshualitt, 2016/02/25 20:50:27]

That should be okay.  We never remove the primitive processor, and it will
always get a chance to modify the key / insert whatever code it wants. 

[Chris Dalton, 2016/02/25 20:57:46]

But the primitive processor might not exist yet, right?

[joshualitt, 2016/02/25 21:00:50]

right, but that should be okay because when we go to flush the draw we'll have a
GrPrimitiveProcessor + GrPipeline combination and at that point the
GrPrimitiveProcessor can do whatever it wants, regardless of the builtinstate
values on the GrPipeline.

[Chris Dalton, 2016/02/25 22:24:24]

I removed info about the fragment position from this class and from GrPocOptInfo
as we decided offline. (It didn't really belong in this class or GrProcOptInfo
anyway.)

 
     if ((flags & GrXferProcessor::kIgnoreColor_OptFlag) ||
         (flags & GrXferProcessor::kOverrideColor_OptFlag)) {
         *firstColorProcessorIdx = pipelineBuilder.numColorFragmentProcessors();
     } else {
-        if (colorPOI.readsFragPosition()) {
-            fReadsFragPosition = true;
-        }
+        fBuiltInState |= colorPOI.builtInState();
     }
 
     if (flags & GrXferProcessor::kIgnoreCoverage_OptFlag) {
         *firstCoverageProcessorIdx = pipelineBuilder.numCoverageFragmentProcessors();
     } else {
-        if (coveragePOI.readsFragPosition()) {
-            fReadsFragPosition = true;
-        }
+        fBuiltInState |= coveragePOI.builtInState();
     }
 }