Fix extensions NSS/BoringSSL dependencies

Fix extensions NSS/BoringSSL dependencies

The NSS dependency should be guarded by a use_openssl check. BoringSSL and NSS
cannot be linked together as they define some of the same symbols. Update BUILD.gn
analogously by depending on //crypto:platform.

Also condition nss in build/all.gyp on use_openssl in preparation for
https://codereview.chromium.org/694643002/ which will disable the nss and nspr
targets altogether.

BUG=429021
Committed: https://crrev.com/d1be6eac818a2f9b35973814c9ff1740fdca2863
Cr-Commit-Position: refs/heads/master@{#302325}

[Ryan Sleevi, 2014-10-30 23:07:28]

rsleevi@chromium.org changed reviewers:
+ rsleevi@chromium.org

[Ryan Sleevi, 2014-10-30 23:07:29]

lgtm

[davidben, 2014-10-30 23:21:48]

davidben@chromium.org changed reviewers:
+ scheib@chromium.org

[davidben, 2014-10-30 23:21:49]

+scheib for extensions OWNERS

[scheib, 2014-10-31 00:49:18]

extensions* lgtm

"Excise it from all.gyp too while I'm here" didn't make sense to me as I don't
see a removal from all.gyp. This patch comment is not readily understandable to
me, wouldn't hurt to be more explicit/descriptive and remove metaphore 'poison
pill'.

[scheib, 2014-10-31 00:53:45]

https://codereview.chromium.org/686693004/diff/40001/extensions/browser/BUILD.gn
File extensions/browser/BUILD.gn (right):

https://codereview.chromium.org/686693004/diff/40001/extensions/browser/BUILD...
extensions/browser/BUILD.gn:22: "//crypto:platform",
This doesn't seem to be addressed in patch comment.

[davidben, 2014-10-31 05:56:48]

Rephrased the description. How is it now?

https://codereview.chromium.org/686693004/diff/40001/extensions/browser/BUILD.gn
File extensions/browser/BUILD.gn (right):

https://codereview.chromium.org/686693004/diff/40001/extensions/browser/BUILD...
extensions/browser/BUILD.gn:22: "//crypto:platform",
On 2014/10/31 00:53:45, scheib wrote:
> This doesn't seem to be addressed in patch comment.

//crypto:platform will depend on the appropriate crypto and SSL library so you
don't have to condition on something complex.

[scheib, 2014-10-31 19:30:27]

lgtm again ;) Thanks for rewording the description!

[davidben, 2014-10-31 20:07:38]

The CQ bit was checked by davidben@chromium.org

[commit-bot: I haz the power, 2014-10-31 20:09:00]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/686693004/40001

[commit-bot: I haz the power, 2014-10-31 21:00:17]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2014-10-31 21:00:49]

Patchset 3 (id:??) landed as
https://crrev.com/d1be6eac818a2f9b35973814c9ff1740fdca2863
Cr-Commit-Position: refs/heads/master@{#302325}