remove unused dynamicwstream.snapshotAsData()

Checking to invalidate this on every write() call has a measurable cost, so removing it both simplifies the class and speeds it up.

BUG=skia:

Change-Id: Idf0baa265c9a0b5d26d82fce948c61ed9b0810b1
Reviewed-on: https://skia-review.googlesource.com/6096
Reviewed-by: Ben Wagner <bungeman@google.com>
Reviewed-by: Mike Klein <mtklein@chromium.org>
Commit-Queue: Mike Reed <reed@google.com>
diff --git a/tests/PDFGlyphsToUnicodeTest.cpp b/tests/PDFGlyphsToUnicodeTest.cpp
index b3ee2d8..a256c93 100644
--- a/tests/PDFGlyphsToUnicodeTest.cpp
+++ b/tests/PDFGlyphsToUnicodeTest.cpp
@@ -15,14 +15,19 @@
 
 static bool stream_equals(const SkDynamicMemoryWStream& stream, size_t offset,
                           const char* buffer, size_t len) {
-    sk_sp<SkData> data = stream.snapshotAsData();
-    if (offset + len > data->size()) {
-        return false;
-    }
     if (len != strlen(buffer)) {
         return false;
     }
-    return memcmp(data->bytes() + offset, buffer, len) == 0;
+
+    const size_t streamSize = stream.bytesWritten();
+
+    if (offset + len > streamSize) {
+        return false;
+    }
+
+    SkAutoTMalloc<char> data(streamSize);
+    stream.copyTo(data.get());
+    return memcmp(data.get() + offset, buffer, len) == 0;
 }
 
 DEF_TEST(SkPDF_ToUnicode, reporter) {