Add isUnblended query to GrDrawState.

src/gpu/GrDrawState.h

Index: src/gpu/GrDrawState.h
diff --git a/src/gpu/GrDrawState.h b/src/gpu/GrDrawState.h
index 15df975d73c4470d5c1e0b83a85ae77c96e4fe9a..ac29ffc87cb736df25ca26ed7b58b3b27e7ae1b5 100644
--- a/src/gpu/GrDrawState.h
+++ b/src/gpu/GrDrawState.h
@@ -159,6 +159,13 @@ public:
      */
     bool hasSolidCoverage() const;
 
+    /**
+     * Determines whether or not a draw will do any blending with the current draw state. For it to
+     * be unblended, it must have solid coverage, have final blend coeffs [1,0], and no effect can

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

Can we not document the implementation but rather the meaning to the caller?
Something like "If this returns true then the render target destination pixel
values will not be read for blending during the draw."

Maybe we should call it willBlendWithDst()? (Of course that'd reverse the
boolean sense of it.)

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

Done.

+     * readDst (otherwise custom blending will occur with in a fragment stage).
+     */
+    bool isUnblended() const;
+
     /// @}
 
     ///////////////////////////////////////////////////////////////////////////