commit 1424c80d9e0fb51679a5e6b17c001d20cc7571f5
author Todd Wang <toddw@google.com> Mon Jan 11 19:53:44 2016 -0800
committer Todd Wang <toddw@google.com> Mon Jan 11 19:53:45 2016 -0800
tree 2c02f26b4b1b927a8de0c8cf62ea450130b3255b
parent 132338cae6c139a8fd8b08b7fefa914208e6e387

textutil: PrefixLineWriter should make single-line writes.

I realized that the whole point of buffering in PrefixLineWriter
is to ensure each underlying Write call contains a full line.
That ensures that if we have multiple PrefixLineWriters writing
out to os.Stdout, we won't be interleaving separate lines.

Note that if we didn't need this property, we could implement
PrefixLineWriter without any buffering or Flush.

So I've changed PrefixLineWriter to ensure single-line-Write.
Also changed to add '\n' to unterminated data when flushed.

Change-Id: I682fac1066bb9989cb232008a7c67959cb2f730a