Implemented transparent gradients

src/pdf/SkPDFShader.h

Index: src/pdf/SkPDFShader.h
diff --git a/src/pdf/SkPDFShader.h b/src/pdf/SkPDFShader.h
index f41bdf038e6b7276c88f680924e2c0e91feb53dc..62bd5499ada0bff5c3130caed581560e7ca1d4cb 100644
--- a/src/pdf/SkPDFShader.h
+++ b/src/pdf/SkPDFShader.h
@@ -57,6 +57,8 @@ protected:
     // This should be made a hash table if performance is a problem.
     static SkTDArray<ShaderCanonicalEntry>& CanonicalShaders();
     static SkBaseMutex& CanonicalShadersMutex();
+
+    static SkPDFObject* GetPDFShaderByState(State* shaderState);

[vandebo (ex-Chrome), 2013/07/12 21:41:44]

At the least this should document that it consumes the state that's passed in. 
But it'd probably be better if it didn't - that may be counter to what I've said
before, sorry if so.

[ducky, 2013/07/12 23:32:34]

It would be cleaner if it didn't, but it needs to be able to transfer ownership
of the shaderState from GetPDFShaderByState(...) to the newly created
SkPDFShader.

Otherwise, either:
- each SkPDFShader instantiation would need to copy the state, which is probably
bad from a performance standpoint and having extra code.
- or SkPDFShader::State would need to be reference-counted, so that an
additional ref() can be done if it is part of a new SkPDFShader object.

Thoughts?

     static void RemoveShader(SkPDFObject* shader);
 
     SkPDFShader();