[telemetry] Add support for requesting memory dumps via extension API

[telemetry] Add support for requesting memory dumps via extension API

This patch (together with https://codereview.chromium.org/1245233004/)
will allow telemetry memory page interactions to request memory dumps
as follows:

  action_runner.tab.DumpMemory()

Note that this patch is a replacement for
https://codereview.chromium.org/1224083015/.

BUG=505826

[petrcermak, 2015-07-24 12:35:16]

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

[Primiano Tucci (use gerrit), 2015-07-24 14:33:29]

primiano@chromium.org changed reviewers:
+ nednguyen@chromium.org, nednguyen@google.com

[Primiano Tucci (use gerrit), 2015-07-24 14:33:29]

LGTM once ned approves.
Ned: apologies for the double round. We had to change strategy and move from
devtools to a JS extension. Petr or Nat can explain the details and the reasons
offline.
Conveniently this one looks easier than the devtools version.

Thanks,
Primaino

https://codereview.chromium.org/1257693002/diff/1/tools/telemetry/telemetry/i...
File tools/telemetry/telemetry/internal/browser/tab.py (right):

https://codereview.chromium.org/1257693002/diff/1/tools/telemetry/telemetry/i...
tools/telemetry/telemetry/internal/browser/tab.py:282:
'window.__telemetry_memory_dump_guid', timeout)
maybe you walso want to clear the global __telemetry...guid here?

[nednguyen, 2015-07-24 14:50:46]

On 2015/07/24 14:33:29, Primiano Tucci (OOO til Aug 9) wrote:
> LGTM once ned approves.
> Ned: apologies for the double round. We had to change strategy and move from
> devtools to a JS extension. Petr or Nat can explain the details and the
reasons
> offline.
> Conveniently this one looks easier than the devtools version.
> 
> Thanks,
> Primaino
> 
>
https://codereview.chromium.org/1257693002/diff/1/tools/telemetry/telemetry/i...
> File tools/telemetry/telemetry/internal/browser/tab.py (right):
> 
>
https://codereview.chromium.org/1257693002/diff/1/tools/telemetry/telemetry/i...
> tools/telemetry/telemetry/internal/browser/tab.py:282:
> 'window.__telemetry_memory_dump_guid', timeout)
> maybe you walso want to clear the global __telemetry...guid here?

lgtm

Would love to hear the explanation. I vaguely remember that these js command can
only affect the current renderer process, and you want the memory dump to be
global to the browser?

[petrcermak, 2015-07-29 16:40:16]

After some discussions we decided to go back to the original DevTools API
solution (https://codereview.chromium.org/1224083015/), so this patch was
abandoned.