Limit the maximum buffer size of SkRawBufferedStream

cherry-pick of c04df21bb624e299440ce8b56495ec109d4e824e into chrome/m50
for nyc-dev.

BUG=b/27475341
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1783683003
NOTREECHECKS=true
NOTRY=true
NOPRESUBMIT=true

Review URL: https://codereview.chromium.org/1783683003
1 file changed