CFI: Enable stack traces in renderer process in non-official CFI builds.

CFI: Enable stack traces in renderer process in non-official CFI builds.

A CFI failure causes a SIGILL signal to be raised, and the most likely
place for a failure to occur is in the renderer. By printing a stack trace
we provide developers with a basic set of information about CFI failures,
and allow crashes to be disambiguated by ClusterFuzz.

BUG=464797
R=jln@chromium.org,jam@chromium.org

Committed: https://crrev.com/ed9ea9af2cf1ab10d0e5ecaaa008b19fe980a4aa
Cr-Commit-Position: refs/heads/master@{#341833}

[pcc1, 2015-08-04 20:20:16]

Ping.

[jln (very slow on Chromium), 2015-08-04 20:25:57]

lgtm (But I'm not Nico)

[pcc1, 2015-08-04 20:36:02]

pcc@chromium.org changed reviewers:
+ jam@chromium.org, jln@chromium.org
- thakis@chromium.org

[pcc1, 2015-08-04 20:37:24]

On 2015/08/04 20:25:57, jln wrote:
> lgtm (But I'm not Nico)

Thanks. Adding jam@ for content/renderer as I accidentally picked the wrong
reviewers for this one.

[jam, 2015-08-04 23:08:00]

lgtm

[pcc1, 2015-08-04 23:11:25]

The CQ bit was checked by pcc@chromium.org

[commit-bot: I haz the power, 2015-08-04 23:13:02]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1269673003/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1269673003/1

[commit-bot: I haz the power, 2015-08-05 00:47:35]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-08-05 00:48:24]

Patchset 1 (id:??) landed as
https://crrev.com/ed9ea9af2cf1ab10d0e5ecaaa008b19fe980a4aa
Cr-Commit-Position: refs/heads/master@{#341833}