Request char* return type explicitly from rtc::Buffer::data()

Request char* return type explicitly from rtc::Buffer::data()

rtc::Buffer::data() will soon start defaulting to uint8_t* for its
return type, so we have to start requesting char* explicitly.

Committed: https://crrev.com/356fb21277972ae096eaefacb1e06da106b48bb1
Cr-Commit-Position: refs/heads/master@{#327468}

[kwiberg-chromium, 2015-04-20 12:33:26]

The CQ bit was checked by kwiberg@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-04-20 12:33:53]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1097043002/1

[commit-bot: I haz the power, 2015-04-20 12:33:54]

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

[commit-bot: I haz the power, 2015-04-20 12:33:55]

Dry run: 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.

[kwiberg-chromium, 2015-04-20 12:54:57]

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

[tommi (sloooow) - chröme, 2015-04-24 13:24:54]

The CQ bit was checked by tommi@chromium.org

[tommi (sloooow) - chröme, 2015-04-24 13:24:55]

lgtm

[tommi (sloooow) - chröme, 2015-04-24 13:25:17]

The CQ bit was unchecked by tommi@chromium.org

[tommi (sloooow) - chröme, 2015-04-24 13:25:19]

lgtm

[kwiberg-chromium, 2015-04-29 09:17:58]

The CQ bit was checked by kwiberg@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-04-29 09:18:29]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1097043002/1

[commit-bot: I haz the power, 2015-04-29 10:25:36]

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

[commit-bot: I haz the power, 2015-04-29 10:25:37]

Dry run: This issue passed the CQ dry run.

[kwiberg-chromium, 2015-04-29 11:04:34]

The CQ bit was checked by kwiberg@chromium.org

[commit-bot: I haz the power, 2015-04-29 11:04:38]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1097043002/1

[commit-bot: I haz the power, 2015-04-29 11:05:18]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-04-29 11:06:14]

Patchset 1 (id:??) landed as
https://crrev.com/356fb21277972ae096eaefacb1e06da106b48bb1
Cr-Commit-Position: refs/heads/master@{#327468}