add Make factory to SkMemoryStream (simplify call-sites)

Bug: skia:6888
Change-Id: Ia4e432673ed089a91229697c8dde0489f220000d
Reviewed-on: https://skia-review.googlesource.com/26884
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Mike Reed <reed@google.com>
diff --git a/src/codec/SkCodec.cpp b/src/codec/SkCodec.cpp
index d0958e8..09343e2 100644
--- a/src/codec/SkCodec.cpp
+++ b/src/codec/SkCodec.cpp
@@ -123,8 +123,7 @@
     if (!data) {
         return nullptr;
     }
-    return MakeFromStream(std::unique_ptr<SkStream>(new SkMemoryStream(std::move(data))),
-                                                    nullptr, reader);
+    return MakeFromStream(SkMemoryStream::Make(std::move(data)), nullptr, reader);
 }
 
 SkCodec::SkCodec(int width, int height, const SkEncodedInfo& info,