MockAudioEncoder: Use a dedicated marker method for test expectations

MockAudioEncoder: Use a dedicated marker method for test expectations

This makes the sequence of expected calls easier to read. Also, we can
save one line and get rid of a gmock warning by expecting the
MockAudioEncoder object to be destroyed at the end of the test instead
of making a final marker call.

Committed: https://crrev.com/9b66d3ba608b33515420b6fe658afed7d5b19f18
Cr-Commit-Position: refs/heads/master@{#9916}

[kwiberg-webrtc, 2015-09-10 11:31:30]

kwiberg@webrtc.org changed reviewers:
+ henrik.lundin@webrtc.org

[kwiberg-webrtc, 2015-09-10 11:31:55]

Prerequisite for https://codereview.webrtc.org/1331853002/.

[hlundin-webrtc, 2015-09-10 12:01:14]

Nice. LGTM.

[kwiberg-webrtc, 2015-09-10 12:06:28]

The CQ bit was checked by kwiberg@webrtc.org

[commit-bot: I haz the power, 2015-09-10 12:06:37]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1331793003/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1331793003/1

[commit-bot: I haz the power, 2015-09-10 12:09:49]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-09-10 12:09:57]

Patchset 1 (id:??) landed as
https://crrev.com/9b66d3ba608b33515420b6fe658afed7d5b19f18
Cr-Commit-Position: refs/heads/master@{#9916}