android_webview: stop using system libjpeg.

android_webview: stop using system libjpeg.

To support unbundled updates we need to stop depending on system
libraries. Disable using the system version of libjpeg and instead link
Chromium's libjpeg_turbo.

This increases binary size by ~120KB.

BUG=409851
Committed: https://crrev.com/7c8c58068cdf2997d338cd0b6e3109c5f773dbe6
Cr-Commit-Position: refs/heads/master@{#293663}

[Torne, 2014-09-05 13:30:14]

torne@chromium.org changed reviewers:
+ benm@chromium.org

[Torne, 2014-09-05 14:21:59]

torne@chromium.org changed reviewers:
+ brettw@chromium.org

[Torne, 2014-09-05 14:22:00]

+brettw for libjpeg gyp/gn changes

[benm (inactive), 2014-09-05 14:27:20]

lgtm

[brettw, 2014-09-05 23:25:32]

lgtm

[Torne, 2014-09-06 09:14:59]

The CQ bit was checked by torne@chromium.org

[commit-bot: I haz the power, 2014-09-06 09:16:56]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/torne@chromium.org/548513002/1

[commit-bot: I haz the power, 2014-09-06 13:49:45]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-09-06 13:49:46]

Exceeded time limit waiting for builds to trigger.

[Torne, 2014-09-07 12:39:29]

The CQ bit was checked by torne@chromium.org

[commit-bot: I haz the power, 2014-09-07 12:40:32]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/torne@chromium.org/548513002/1

[commit-bot: I haz the power, 2014-09-07 12:41:56]

Committed patchset #1 (id:1) as 13a7d8ea22caccd3d98e37d6424a3e78805b1ccf

[Noel Gordon, 2014-09-07 13:07:41]

120k _and_ 2x-3x faster.

[commit-bot: I haz the power, 2014-09-10 03:44:17]

Patchset 1 (id:??) landed as
https://crrev.com/7c8c58068cdf2997d338cd0b6e3109c5f773dbe6
Cr-Commit-Position: refs/heads/master@{#293663}