[Telemetry] Include debugging info when foreground tab is missing

[Telemetry] Include debugging info when foreground tab is missing

Raise a subclass of exceptions.Error when the foreground tab is not
found, so that more debug information is included in the logs.

BUG=chromium:760901
Review-Url: https://chromiumcodereview.appspot.com/3015633002
Committed: https://chromium.googlesource.com/external/github.com/catapult-project/catapult/+/6926f20b399dfe1cafe1d1867912cc799f434a8b

[perezju, 2017-09-20 11:57:31]

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

[nednguyen, 2017-09-20 12:10:06]

lgtm

[perezju, 2017-09-20 12:43:57]

The CQ bit was checked by perezju@chromium.org

[commit-bot: I haz the power, 2017-09-20 12:43:59]

CQ is trying da patch.

Follow status at:
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-09-20 13:16:10]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1505911437307010, "parent_rev":
"3f9a1ba77bbbe6ccf9551db7d05354296c555526", "commit_rev":
"6926f20b399dfe1cafe1d1867912cc799f434a8b"}

[commit-bot: I haz the power, 2017-09-20 13:16:13]

Description was changed from

==========
[Telemetry] Include debugging info when foreground tab is missing

Raise a subclass of exceptions.Error when the foreground tab is not
found, so that more debug information is included in the logs.

BUG=chromium:760901
==========

to

==========
[Telemetry] Include debugging info when foreground tab is missing

Raise a subclass of exceptions.Error when the foreground tab is not
found, so that more debug information is included in the logs.

BUG=chromium:760901

Review-Url: https://chromiumcodereview.appspot.com/3015633002
Committed:
https://chromium.googlesource.com/external/github.com/catapult-project/catapu...
==========

[commit-bot: I haz the power, 2017-09-20 13:16:15]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/external/github.com/catapult-project/catapu...