Add isUnblended query to GrDrawState.

src/gpu/GrDrawState.cpp

Index: src/gpu/GrDrawState.cpp
diff --git a/src/gpu/GrDrawState.cpp b/src/gpu/GrDrawState.cpp
index c82c5adad1f771354e711e1ce149234d8ee77acf..a6e4a96083f7e350cd20b48c400d8c69f05e862e 100644
--- a/src/gpu/GrDrawState.cpp
+++ b/src/gpu/GrDrawState.cpp
@@ -742,3 +742,20 @@ bool GrDrawState::srcAlphaWillBeOne() const {
     return inoutColor.isOpaque();
 }
 
+bool GrDrawState::isUnblended() const {
+    if (!this->hasSolidCoverage()) {
+        return false;
+    }
+
+    bool srcAIsOne = this->srcAlphaWillBeOne();
+    GrBlendCoeff srcCoeff = this->getSrcBlendCoeff();
+    GrBlendCoeff dstCoeff = this->getDstBlendCoeff();
+    bool dstCoeffIsZero = kZero_GrBlendCoeff == dstCoeff ||

[bsalomon, 2014/11/11 20:49:56]

The fact that the blend opts code doesn't directly update the coeffs is weird.
Can we make this something like

if (kISA_GrBlendCoeff == dstCoeff && srcAIsOne) {
    dstCoeff == kZero_GrBlendCoeff;
}

[egdaniel, 2014/11/11 21:05:55]

Done.

+                          (kISA_GrBlendCoeff == dstCoeff && srcAIsOne);
+    if (kOne_GrBlendCoeff != srcCoeff || !dstCoeffIsZero || this->willEffectReadDstColor()) {
+        return false;
+    }
+
+    return true;
+}
+