Add capture snapshot as data to SkWriter32, use it to optimise record->playback.

src/core/SkPicturePlayback.cpp

Index: src/core/SkPicturePlayback.cpp
diff --git a/src/core/SkPicturePlayback.cpp b/src/core/SkPicturePlayback.cpp
index b546d397c04617570c7534c1ed338f451abc0af0..3b7c34bf84161a36f267b749ca17b55bb37703da 100644
--- a/src/core/SkPicturePlayback.cpp
+++ b/src/core/SkPicturePlayback.cpp
@@ -69,10 +69,12 @@ SkPicturePlayback::SkPicturePlayback(const SkPictureRecord& record, bool deepCop
     record.validate(record.writeStream().bytesWritten(), 0);
     const SkWriter32& writer = record.writeStream();
     init();
+    SkASSERT(!fOpData);
     if (writer.bytesWritten() == 0) {
         fOpData = SkData::NewEmpty();
         return;
     }
+    fOpData = writer.snapshotAsData();
 
     fBoundingHierarchy = record.fBoundingHierarchy;
     fStateTree = record.fStateTree;
@@ -84,14 +86,6 @@ SkPicturePlayback::SkPicturePlayback(const SkPictureRecord& record, bool deepCop
         fBoundingHierarchy->flushDeferredInserts();
     }
 
-    {
-        size_t size = writer.bytesWritten();
-        void* buffer = sk_malloc_throw(size);
-        writer.flatten(buffer);
-        SkASSERT(!fOpData);
-        fOpData = SkData::NewFromMalloc(buffer, size);
-    }
-
     // copy over the refcnt dictionary to our reader
     record.fFlattenableHeap.setupPlaybacks();