Add Tracing.requestMemoryDump method stub to DevTools API

Add Tracing.requestMemoryDump method stub to DevTools API

This patch is the first part of a 3-sided patch which adds
Tracing.requestMemoryDump method to DevTools API:

  1. Add Tracing.requestMemoryDump method stub to DevTools API
     this patch [Chromium]
  2. Add Tracing.requestMemoryDump method to DevTools API (protocol)
     https://codereview.chromium.org/1235393005/ [Blink]
  3. Add Tracing.requestMemoryDump method to DevTools API (tracing
     handler)
     https://codereview.chromium.org/1232313004/ [Chromium]

Proposal:
https://docs.google.com/document/d/190-URzSjfsiXNeyke86z85-5ctuqsC_RoX1J1uJTwIQ/edit?usp=sharing

BUG=505826
Committed: https://crrev.com/4fea05d9046efdd564d6a29ae82d8472fc366f9a
Cr-Commit-Position: refs/heads/master@{#340553}

[petrcermak, 2015-07-27 18:06:16]

petrcermak@chromium.org changed reviewers:
+ pfeldman@chromium.org

[petrcermak, 2015-07-27 18:06:17]

PTAL.

Thanks,
Petr

[pfeldman, 2015-07-27 18:53:07]

lgtm, yes, that's the sequence of landing until repos merge.

[petrcermak, 2015-07-27 18:54:33]

The CQ bit was checked by petrcermak@chromium.org

[commit-bot: I haz the power, 2015-07-27 18:55:12]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1255213003/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1255213003/1

[commit-bot: I haz the power, 2015-07-27 20:41:49]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-07-27 20:43:12]

Patchset 1 (id:??) landed as
https://crrev.com/4fea05d9046efdd564d6a29ae82d8472fc366f9a
Cr-Commit-Position: refs/heads/master@{#340553}