[Telemetry] Small fixes to power monitoring

[Telemetry] Small fixes to power monitoring

* Fix FD leak when reading output file.
* Update OS X version check.

BUG=None

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=251059

[marja, 2014-02-13 13:55:43]

lgtm

[jeremy, 2014-02-13 13:58:25]

The CQ bit was checked by jeremy@chromium.org

[commit-bot: I haz the power, 2014-02-13 13:58:33]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/jeremy@chromium.org/163183003/1

[tonyg, 2014-02-13 15:30:37]

lgtm

https://codereview.chromium.org/163183003/diff/1/tools/telemetry/telemetry/co...
File tools/telemetry/telemetry/core/platform/mac_platform_backend.py (left):

https://codereview.chromium.org/163183003/diff/1/tools/telemetry/telemetry/co...
tools/telemetry/telemetry/core/platform/mac_platform_backend.py:83: return
open(self._output_filename, 'rb').read()
Just for my knowledge, does this really leak? Or just delay collection of the fd
until gc runs?

I use this pattern a lot and like the brevity, but will avoid it if it really
leaks.

[commit-bot: I haz the power, 2014-02-13 16:37:13]

Change committed as 251059

[jeremy, 2014-02-16 12:48:45]

On 2014/02/13 15:30:37, tonyg wrote:
> lgtm
> 
>
https://codereview.chromium.org/163183003/diff/1/tools/telemetry/telemetry/co...
> File tools/telemetry/telemetry/core/platform/mac_platform_backend.py (left):
> 
>
https://codereview.chromium.org/163183003/diff/1/tools/telemetry/telemetry/co...
> tools/telemetry/telemetry/core/platform/mac_platform_backend.py:83: return
> open(self._output_filename, 'rb').read()
> Just for my knowledge, does this really leak? Or just delay collection of the
fd
> until gc runs?
> 
> I use this pattern a lot and like the brevity, but will avoid it if it really
> leaks.

You're right, this is not a leak - gc should close the FD...