Use local variable for out parameter rather than direct use of ivar

Use local variable for out parameter rather than direct use of ivar

- Resolves spurious static analyzer warning about response_ being potentially leaked due to the retain in Xcode 6.3 and later.

I'm submitting this on behalf of Brian Moore.

R=qsr@chromium.org

Committed: https://code.google.com/p/google-breakpad/source/detail?r=1460

[ivanpe, 2015-06-10 18:32:31]

ivanpe@chromium.org changed reviewers:
+ blundell@chromium.org, dmaclach@gmail.com, qsr@chromium.org

[qsr, 2015-06-11 09:29:27]

lgtm

[ivanpe, 2015-06-20 00:32:57]

Committed patchset #1 (id:1) manually as r1460 (presubmit successful).