Support tracing flow events v2 in Blink

Support tracing flow events v2 in Blink

This includes passing an additional bindId parameter to Chrome, and increasing the size of the flags field from char to int (it's been an int in Chrome for some time).

Prerequisite (Chrome side CL) is https://codereview.chromium.org/1354453002/
Original review URL: https://codereview.chromium.org/1347113004/

TBR=tkent@chromium.org
BUG=532726
Committed: https://crrev.com/73dd7bd7dfda7e1bf190f10ad6718a662207697d
Cr-Commit-Position: refs/heads/master@{#350606}

[oystein (OOO til 10th of July), 2015-09-24 00:22:57]

The CQ bit was checked by oysteine@chromium.org

[commit-bot: I haz the power, 2015-09-24 00:24:25]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1359973003/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1359973003/1

[commit-bot: I haz the power, 2015-09-24 01:44:49]

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

[commit-bot: I haz the power, 2015-09-24 01:44:50]

Try jobs failed on following builders:
  mac_chromium_rel_ng on tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_rel_...)

[oystein (OOO til 10th of July), 2015-09-24 17:20:47]

The CQ bit was checked by oysteine@chromium.org

[commit-bot: I haz the power, 2015-09-24 17:21:52]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1359973003/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1359973003/1

[commit-bot: I haz the power, 2015-09-24 18:12:04]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-09-24 18:13:14]

Patchset 1 (id:??) landed as
https://crrev.com/73dd7bd7dfda7e1bf190f10ad6718a662207697d
Cr-Commit-Position: refs/heads/master@{#350606}

[tkent, 2015-10-07 00:35:19]

lgtm