[Tracing] Update sync_id to be string type for clock sync

[Tracing] Update sync_id to be string type for clock sync

The sync_id was int. This CL changes its type to string so
that it is more flexible and consistent with DevTools API's
preference. Now the tracing controller uses
base::GenerateGUID() to generate the ID.

BUG=542390
Committed: https://crrev.com/d0e022849450bcb65cb27a3f50d116bfe3635d5d
Cr-Commit-Position: refs/heads/master@{#371964}

[Zhen Wang, 2016-01-27 17:27:43]

Description was changed from

==========
[Tracing] Update sync_id to be string type for clock sync

BUG=542390
==========

to

==========
[Tracing] Update sync_id to be string type for clock sync

The sync_id was int. This CL changes its type to string so
that it is more flexible and consistent with DevTools API's
preference. Now the tracing controller uses 
base::GenerateGUID() to generate the ID.

BUG=542390
==========

[Zhen Wang, 2016-01-27 17:29:23]

zhenw@chromium.org changed reviewers:
+ oysteine@chromium.org

[Zhen Wang, 2016-01-27 17:29:23]

ptal

[oystein (OOO til 10th of July), 2016-01-28 00:41:44]

lgtm

[Zhen Wang, 2016-01-28 00:53:25]

The CQ bit was checked by zhenw@chromium.org

[commit-bot: I haz the power, 2016-01-28 00:54:55]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1644653002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1644653002/1

[commit-bot: I haz the power, 2016-01-28 02:09:18]

Description was changed from

==========
[Tracing] Update sync_id to be string type for clock sync

The sync_id was int. This CL changes its type to string so
that it is more flexible and consistent with DevTools API's
preference. Now the tracing controller uses 
base::GenerateGUID() to generate the ID.

BUG=542390
==========

to

==========
[Tracing] Update sync_id to be string type for clock sync

The sync_id was int. This CL changes its type to string so
that it is more flexible and consistent with DevTools API's
preference. Now the tracing controller uses 
base::GenerateGUID() to generate the ID.

BUG=542390
==========

[commit-bot: I haz the power, 2016-01-28 02:09:18]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-01-28 02:11:13]

Description was changed from

==========
[Tracing] Update sync_id to be string type for clock sync

The sync_id was int. This CL changes its type to string so
that it is more flexible and consistent with DevTools API's
preference. Now the tracing controller uses 
base::GenerateGUID() to generate the ID.

BUG=542390
==========

to

==========
[Tracing] Update sync_id to be string type for clock sync

The sync_id was int. This CL changes its type to string so
that it is more flexible and consistent with DevTools API's
preference. Now the tracing controller uses
base::GenerateGUID() to generate the ID.

BUG=542390

Committed: https://crrev.com/d0e022849450bcb65cb27a3f50d116bfe3635d5d
Cr-Commit-Position: refs/heads/master@{#371964}
==========

[commit-bot: I haz the power, 2016-01-28 02:11:13]

Patchset 1 (id:??) landed as
https://crrev.com/d0e022849450bcb65cb27a3f50d116bfe3635d5d
Cr-Commit-Position: refs/heads/master@{#371964}