Check if null pointer is provided in DeviceWatcher callbacks

Check if null pointer is provided in DeviceWatcher callbacks

Callbacks from DeviceWatcher events occasionally provide null pointers for
device information and handle interfaces. For example,
Midi{In,Out}Port.FromIdAsync return null handles in IAsyncOperation results if
the requested device is occupied by another application using legacy APIs.
DeviceWatcher.Removed event is also observed to provide null
IDeviceInformationUpdate pointers, but we are still unable to reproduce the
problem.

Additional checks in DeviceWatcher callbacks should be added to prevent crashes
before shipping this feature as default on Windows 10 hosts. We may also want to
collect statistics on this issue in the future.

BUG=645403
Committed: https://crrev.com/500c32be9f547a6e4ea818672ed62e34399b1916
Cr-Commit-Position: refs/heads/master@{#419694}

[Shao-Chuan Lee, 2016-09-20 05:35:39]

shaochuan@chromium.org changed reviewers:
+ toyoshim@chromium.org

[Shao-Chuan Lee, 2016-09-20 05:35:40]

PTAL
Maybe we should file a new bug for this and/or report to Microsoft?

[Takashi Toyoshima, 2016-09-20 06:43:41]

LGTM.

Reporting to MS sounds fine, but I don't know how. Can you ask Chrome Windows
port team?

[Shao-Chuan Lee, 2016-09-20 06:46:19]

The CQ bit was checked by shaochuan@chromium.org

[commit-bot: I haz the power, 2016-09-20 06:46:28]

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, 2016-09-20 08:11:18]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-09-20 08:14:35]

Description was changed from

==========
Check if null pointer is provided in DeviceWatcher callbacks

Callbacks from DeviceWatcher events occasionally provide null pointers for
device information and handle interfaces. For example,
Midi{In,Out}Port.FromIdAsync return null handles in IAsyncOperation results if
the requested device is occupied by another application using legacy APIs.
DeviceWatcher.Removed event is also observed to provide null
IDeviceInformationUpdate pointers, but we are still unable to reproduce the
problem.

Additional checks in DeviceWatcher callbacks should be added to prevent crashes
before shipping this feature as default on Windows 10 hosts. We may also want to
collect statistics on this issue in the future.

BUG=645403
==========

to

==========
Check if null pointer is provided in DeviceWatcher callbacks

Callbacks from DeviceWatcher events occasionally provide null pointers for
device information and handle interfaces. For example,
Midi{In,Out}Port.FromIdAsync return null handles in IAsyncOperation results if
the requested device is occupied by another application using legacy APIs.
DeviceWatcher.Removed event is also observed to provide null
IDeviceInformationUpdate pointers, but we are still unable to reproduce the
problem.

Additional checks in DeviceWatcher callbacks should be added to prevent crashes
before shipping this feature as default on Windows 10 hosts. We may also want to
collect statistics on this issue in the future.

BUG=645403

Committed: https://crrev.com/500c32be9f547a6e4ea818672ed62e34399b1916
Cr-Commit-Position: refs/heads/master@{#419694}
==========

[commit-bot: I haz the power, 2016-09-20 08:14:36]

Patchset 1 (id:??) landed as
https://crrev.com/500c32be9f547a6e4ea818672ed62e34399b1916
Cr-Commit-Position: refs/heads/master@{#419694}