SkPDF: skpdfdocument and skpdfpage use skpdfdevice in a const way

src/pdf/SkPDFShader.cpp

Index: src/pdf/SkPDFShader.cpp
diff --git a/src/pdf/SkPDFShader.cpp b/src/pdf/SkPDFShader.cpp
index 97bca73f63b78d33c5e552736e4702f015277646..da55340d4c518981e94fb76d9b34a9403391b9e2 100644
--- a/src/pdf/SkPDFShader.cpp
+++ b/src/pdf/SkPDFShader.cpp
@@ -1101,8 +1101,10 @@ SkPDFImageShader* SkPDFImageShader::Create(
             SkNEW_ARGS(SkPDFImageShader, (autoState->detach()));
     imageShader->setData(content.get());
 
+    SkAutoTUnref<SkPDFResourceDict> resourceDict(
+            patternDevice->createResourceDict());
     populate_tiling_pattern_dict(imageShader, patternBBox,
-                                 patternDevice->getResourceDict(), finalMatrix);
+                                 resourceDict.get(), finalMatrix);
 
     imageShader->fShaderState->fImage.unlockPixels();