Fix memory leak introduced in http://crrev.com/387863005

NOTRY=true
R=bungeman@google.com, mtklein@google.com

Author: halcanary@google.com

Review URL: https://codereview.chromium.org/395543002
diff --git a/src/pdf/SkPDFStream.cpp b/src/pdf/SkPDFStream.cpp
index 60fce0d..c310998 100644
--- a/src/pdf/SkPDFStream.cpp
+++ b/src/pdf/SkPDFStream.cpp
@@ -114,7 +114,9 @@
                     SkFlate::Deflate(fDataStream.get(), &compressedData));
             SkAssertResult(fDataStream->rewind());
             if (compressedData.getOffset() < this->dataSize()) {
-                this->setData(compressedData.detachAsStream());
+                SkAutoTUnref<SkStream> compressed(
+                        compressedData.detachAsStream());
+                this->setData(compressed.get());
                 insertName("Filter", "FlateDecode");
             }
             fState = kCompressed_State;