Document and test that image_util.WritePngFile requires path end in 'png'.

Document and test that image_util.WritePngFile requires path end in 'png'.

Fix the GPU tests' cloud_storage_test_base to follow this requirement.

BUG=450673
Committed: https://crrev.com/fd59ae6c44ac0388a0d4929cd056231c78c7f0b4
Cr-Commit-Position: refs/heads/master@{#312561}

[Ken Russell (switch to Gerrit), 2015-01-22 01:24:37]

kbr@chromium.org changed reviewers:
+ dtu@chromium.org, flackr@chromium.org, slamm@chromium.org,
sullivan@chromium.org, tonyg@chromium.org

[Ken Russell (switch to Gerrit), 2015-01-22 01:24:38]

Telemetry owners: please review and CQ this CL if it looks OK.

Jamie: once this has landed, you can safely re-land your other CL from
crbug.com/450673 .

[sullivan, 2015-01-22 03:11:23]

lgtm

lgtm after addressing comment in unit test.

https://codereview.chromium.org/865653004/diff/1/tools/telemetry/telemetry/im...
File tools/telemetry/telemetry/image_processing/image_util_unittest.py (right):

https://codereview.chromium.org/865653004/diff/1/tools/telemetry/telemetry/im...
tools/telemetry/telemetry/image_processing/image_util_unittest.py:64:
self.fail('WritePngFile should have thrown an exception')
Doesn't this work?

self.assertRaises(AssertionError, image_util.WritePngFile, orig, temp_file)

code search shows a few dozen other places where assertRaises is called with
AssertionError in chrome:
https://code.google.com/p/chromium/codesearch#search/&q=assertRaises%5C(Asser...

[Ken Russell (switch to Gerrit), 2015-01-22 03:17:04]

https://codereview.chromium.org/865653004/diff/1/tools/telemetry/telemetry/im...
File tools/telemetry/telemetry/image_processing/image_util_unittest.py (right):

https://codereview.chromium.org/865653004/diff/1/tools/telemetry/telemetry/im...
tools/telemetry/telemetry/image_processing/image_util_unittest.py:64:
self.fail('WritePngFile should have thrown an exception')
On 2015/01/22 03:11:23, sullivan wrote:
> Doesn't this work?
> 
> self.assertRaises(AssertionError, image_util.WritePngFile, orig, temp_file)
> 
> code search shows a few dozen other places where assertRaises is called with
> AssertionError in chrome:
>
https://code.google.com/p/chromium/codesearch#search/&q=assertRaises%5C(Asser...

Thanks for the tip. I'm not fluent in either Python or its unittest library.
Done.

[Ken Russell (switch to Gerrit), 2015-01-22 03:17:16]

The CQ bit was checked by kbr@chromium.org

[commit-bot: I haz the power, 2015-01-22 03:18:16]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/865653004/20001

[commit-bot: I haz the power, 2015-01-22 04:20:57]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-01-22 04:21:46]

Patchset 2 (id:??) landed as
https://crrev.com/fd59ae6c44ac0388a0d4929cd056231c78c7f0b4
Cr-Commit-Position: refs/heads/master@{#312561}

[Jamie Madill, 2015-01-22 15:27:20]

On 2015/01/22 04:21:46, I haz the power (commit-bot) wrote:
> Patchset 2 (id:??) landed as
> https://crrev.com/fd59ae6c44ac0388a0d4929cd056231c78c7f0b4
> Cr-Commit-Position: refs/heads/master@{#312561}

Thanks Ken!