Remove GP from drawstate, revision of invariant output for GP

BUG=skia:

Review URL: https://codereview.chromium.org/791743003
diff --git a/src/gpu/effects/GrBitmapTextGeoProc.cpp b/src/gpu/effects/GrBitmapTextGeoProc.cpp
index 1578fd8..9c5e82e 100644
--- a/src/gpu/effects/GrBitmapTextGeoProc.cpp
+++ b/src/gpu/effects/GrBitmapTextGeoProc.cpp
@@ -84,15 +84,15 @@
     return SkToBool(this->inColor()) == SkToBool(gp.inColor());
 }
 
-void GrBitmapTextGeoProc::onComputeInvariantOutput(GrInvariantOutput* inout) const {
+void GrBitmapTextGeoProc::onGetInvariantOutputCoverage(GrInitInvariantOutput* out) const {
     if (GrPixelConfigIsAlphaOnly(this->texture(0)->config())) {
-        inout->mulByUnknownAlpha();
+        out->setUnknownSingleComponent();
     } else if (GrPixelConfigIsOpaque(this->texture(0)->config())) {
-        inout->mulByUnknownOpaqueColor();
-        inout->setUsingLCDCoverage();
+        out->setUnknownOpaqueFourComponents();
+        out->setUsingLCDCoverage();
     } else {
-        inout->mulByUnknownColor();
-        inout->setUsingLCDCoverage();
+        out->setUnknownFourComponents();
+        out->setUsingLCDCoverage();
     }
 }