tree bee78bcbe290463bc346f0fb9ec6d18233bbb440
parent c5748148c56e129e7b5cec7fac0921ce7967d054
author Kenny Root <kroot@google.com> 1360797770 -0800
committer Kenny Root <kroot@google.com> 1360797846 -0800

KeyChain: return null instead of throw

The API documentation says it will return null if the key isn't found.
We get null back from the keystore daemon when it can't retrieve the
data, so just return null back to the API caller.

Change-Id: I42248bd50cbc5f76864bd762aae3faab1c50529d