GN: Change webrtc_base -> rtc_base

GN: Change webrtc_base -> rtc_base

The target was renamed in GYP a while back
and in https://code.google.com/p/webrtc/source/detail?r=8117
for GN. This is the last reference left using the
'webrtc_base' target name.

TBR=tommi@chromium.org

Committed: https://crrev.com/7c9149860a8a0ca24350d2e80dbc280990a0cbb7
Cr-Commit-Position: refs/heads/master@{#313100}

[kjellander_chromium, 2015-01-26 19:13:01]

kjellander@chromium.org changed reviewers:
+ perkj@chromium.org

[kjellander_chromium, 2015-01-26 19:14:18]

kjellander@chromium.org changed reviewers:
+ hellner@chromium.org
- perkj@chromium.org

[hellner1, 2015-01-26 19:17:10]

lgtm

[kjellander_chromium, 2015-01-26 19:20:41]

The CQ bit was checked by kjellander@chromium.org

[commit-bot: I haz the power, 2015-01-26 19:21:53]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/868573003/1

[commit-bot: I haz the power, 2015-01-26 19:21:54]

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

[commit-bot: I haz the power, 2015-01-26 19:21:54]

No LGTM from a valid reviewer yet. Only full committers are accepted.
Even if an LGTM may have been provided, it was from a non-committer,
_not_ a full super star committer.
See http://www.chromium.org/getting-involved/become-a-committer
Note that this has nothing to do with OWNERS files.

[kjellander_chromium, 2015-01-26 19:24:11]

kjellander@chromium.org changed reviewers:
+ tommi@chromium.org

[kjellander_chromium, 2015-01-26 19:24:53]

TBR'ing tommi

[kjellander_chromium, 2015-01-26 19:24:58]

The CQ bit was checked by kjellander@chromium.org

[commit-bot: I haz the power, 2015-01-26 19:26:00]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/868573003/1

[commit-bot: I haz the power, 2015-01-26 19:30:15]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-01-26 19:31:12]

Patchset 1 (id:??) landed as
https://crrev.com/7c9149860a8a0ca24350d2e80dbc280990a0cbb7
Cr-Commit-Position: refs/heads/master@{#313100}