Switch SkPDFStream's internal storage from SkStream to SkData
Motivation: This makes SkPDFStream thread-safe for two threads
serializing it at once, since a SkStream has an internal position.
Updated SkPDFFont, SkPDFGraphicState, and SkPDFPage's use of
SkPDFStream to use the SkData constructor rather than the SkStream
constructor (saving a memcpy).
BUG=skia:2683
Committed: https://skia.googlesource.com/skia/+/c1dfa14b645ae274780f026dd86c9b633fbdad06
R=mtklein@google.com, djsollen@google.com, rmistry@google.com, robertphillips@google.com
Author: halcanary@google.com
Review URL: https://codereview.chromium.org/340783013
16 files changed