SkFontData to use smart pointers.

The SkFontData type is not exposed externally, so any method which uses
it can be updated to use smart pointers without affecting external
users. Updating this first will make updating the public API much
easier.

This also updates SkStreamAsset* SkStream::NewFromFile(const char*) to
std::unique_ptr<SkStreamAsset> SkStream::MakeFromFile(const char*). It
appears that no one outside Skia is currently using SkStream::NewfromFile
so this is a good time to update it as well.

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2339273002

Committed: https://skia.googlesource.com/skia/+/d8c2476a8b1e1e1a1771b17e8dd4db8645914f8c
Review-Url: https://codereview.chromium.org/2339273002
diff --git a/include/core/SkStream.h b/include/core/SkStream.h
index 48ac577..7afce71 100644
--- a/include/core/SkStream.h
+++ b/include/core/SkStream.h
@@ -40,11 +40,9 @@
     virtual ~SkStream() {}
 
     /**
-     *  Attempts to open the specified file, and return a stream to it (using
-     *  mmap if available). On success, the caller is responsible for deleting.
-     *  On failure, returns NULL.
+     *  Attempts to open the specified file as a stream, returns nullptr on failure.
      */
-    static SkStreamAsset* NewFromFile(const char path[]);
+    static std::unique_ptr<SkStreamAsset> MakeFromFile(const char path[]);
 
     /** Reads or skips size number of bytes.
      *  If buffer == NULL, skip size bytes, return how many were skipped.