android: Remove TraceEvent.begin()/end()

android: Remove TraceEvent.begin()/end()

All callers have been moved to onens with explicit event names. Removing
the expensive dumping stack implemntation.

BUG=439118
Committed: https://crrev.com/8e5c0b0f824d35e369d5db10f0c131d12b5e95a3
Cr-Commit-Position: refs/heads/master@{#308356}

[boliu, 2014-12-12 18:58:03]

boliu@chromium.org changed reviewers:
+ nyquist@chromium.org

[boliu, 2014-12-12 18:58:03]

Weee, it's gone!

[nyquist, 2014-12-15 09:33:59]

lgtm \o/

[boliu, 2014-12-15 15:12:14]

The CQ bit was checked by boliu@chromium.org

[commit-bot: I haz the power, 2014-12-15 15:12:26]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/803603002/1

[commit-bot: I haz the power, 2014-12-15 16:03:37]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2014-12-15 16:04:20]

Patchset 1 (id:??) landed as
https://crrev.com/8e5c0b0f824d35e369d5db10f0c131d12b5e95a3
Cr-Commit-Position: refs/heads/master@{#308356}