Process: Fix communication with zygote.

Don't write partial requests, and don't return (or throw) early after
partially reading a response.

bug: 30143607
Change-Id: I5881fdd5e81023cd21fb4d23a471a5031987a1f1
(cherry picked from commit 448be0a62209c977593d81617853a8a428d013df)
(cherry picked from commit 9b0ae9feb67bde7025b25b677d52d77d8341aa97)
1 file changed