Implemented transparent gradients

src/pdf/SkPDFGraphicState.h

Index: src/pdf/SkPDFGraphicState.h
diff --git a/src/pdf/SkPDFGraphicState.h b/src/pdf/SkPDFGraphicState.h
index 64f34f8744ad65d3e8dd976ed13dc6745fc1785e..4f9b7a9867772e848d32fb1e6994bf348bb67ab2 100644
--- a/src/pdf/SkPDFGraphicState.h
+++ b/src/pdf/SkPDFGraphicState.h
@@ -53,9 +53,10 @@ public:
      *  responsibility to unreference it when done.
      *  @param sMask  The form xobject to use as a soft mask.
      *  @param invert Indicates if the alpha of the sMask should be inverted.
+     *  @param alpha  True to use alpha for the sMask, otherwise luminosity.

[vandebo (ex-Chrome), 2013/07/03 17:07:01]

Contrary to what you might see here, we prefer enums to bools for parameter
arguments. It makes things easier to read at the call site.  If you'd like to
clean up the other bool parameter in another CL, that'd be nice.

[ducky, 2013/07/03 23:32:09]

Done.

Does it make sense to turn the other bool parameter into a enum? It makes
intuitive sense as a bool, and calling code uses an inline boolean equality
test.

      */
     static SkPDFGraphicState* GetSMaskGraphicState(SkPDFFormXObject* sMask,
-                                                   bool invert);
+                                                   bool invert, bool alpha);
 
     /** Get a graphic state that only unsets the soft mask. The reference
      *  count of the object is incremented and it is the caller's responsibility