Workaround telemetry CPU problem on Android.

Workaround telemetry CPU problem on Android.

Some devices remove cpu related files from /proc when the cores are
turned off. We assume the frequency is 0 if it's missing.

BUG=417259
Committed: https://crrev.com/096c1e44db5723d9eacff072afa76b48f84728c5
Cr-Commit-Position: refs/heads/master@{#296492}

[nednguyen, 2014-09-24 17:37:04]

nednguyen@google.com changed reviewers:
+ nduca@chromium.org, skyostil@chromium.org, tonyg@chromium.org

[nednguyen, 2014-09-24 17:37:19]

PTAL

[Sami, 2014-09-24 17:49:57]

https://codereview.chromium.org/598093003/diff/1/tools/telemetry/telemetry/co...
File
tools/telemetry/telemetry/core/platform/power_monitor/sysfs_power_monitor.py
(right):

https://codereview.chromium.org/598093003/diff/1/tools/telemetry/telemetry/co...
tools/telemetry/telemetry/core/platform/power_monitor/sysfs_power_monitor.py:123:
if 'No such file or directory' in sample[cpu]:
Could we switch to self._platform.GetFileContents() instead? It will throw an
exception if the file cannot be read -- seems a little more robust than relying
on a particular error.

[nednguyen, 2014-09-24 18:02:01]

https://codereview.chromium.org/598093003/diff/1/tools/telemetry/telemetry/co...
File
tools/telemetry/telemetry/core/platform/power_monitor/sysfs_power_monitor.py
(right):

https://codereview.chromium.org/598093003/diff/1/tools/telemetry/telemetry/co...
tools/telemetry/telemetry/core/platform/power_monitor/sysfs_power_monitor.py:123:
if 'No such file or directory' in sample[cpu]:
On 2014/09/24 17:49:57, Sami wrote:
> Could we switch to self._platform.GetFileContents() instead? It will throw an
> exception if the file cannot be read -- seems a little more robust than
relying
> on a particular error.

Done.

[nednguyen, 2014-09-24 18:13:06]

nednguyen@google.com changed reviewers:
+ dtu@chromium.org

[nednguyen, 2014-09-24 18:17:19]

Patchset #2 (id:20001) has been deleted

[tonyg, 2014-09-24 18:23:40]

lgtm

[nednguyen, 2014-09-24 18:26:45]

The CQ bit was checked by nednguyen@google.com

[commit-bot: I haz the power, 2014-09-24 18:28:40]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/598093003/40001

[commit-bot: I haz the power, 2014-09-24 19:40:45]

Committed patchset #2 (id:40001) as 69fa8a7c88642321ea73b8352661b50ed2f534aa

[commit-bot: I haz the power, 2014-09-24 19:41:22]

Patchset 2 (id:??) landed as
https://crrev.com/096c1e44db5723d9eacff072afa76b48f84728c5
Cr-Commit-Position: refs/heads/master@{#296492}