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..0b292e932a3c0dd557a81572c59df59ffc6b7a98 100644
--- a/src/pdf/SkPDFShader.h
+++ b/src/pdf/SkPDFShader.h
@@ -57,6 +57,11 @@ protected:
     // This should be made a hash table if performance is a problem.
     static SkTDArray<ShaderCanonicalEntry>& CanonicalShaders();
     static SkBaseMutex& CanonicalShadersMutex();
+
+    // This is an internal method.
+    // CanonicalShadersMutex() should already be acquired.
+    // This also takes ownership of shaderState.
+    static SkPDFObject* GetPDFShaderByState(State* shaderState);
     static void RemoveShader(SkPDFObject* shader);
 
     SkPDFShader();