Make navigator.usb open the DeviceManager connection lazily.

Make navigator.usb open the DeviceManager connection lazily.

This change makes it so that accessing the navigator.usb object does not
automatically cause Blink to connect to the browser process for an
instance of the DeviceManager service. This is useful because it makes
it easier for tests to register a Mojo service override before the
connection is made.

BUG=None

Review-Url: https://codereview.chromium.org/2751173004
Cr-Commit-Position: refs/heads/master@{#457484}
Committed: https://chromium.googlesource.com/chromium/src/+/7f238dd47bf022bc3f40fd64131c5a2784a9da3a

[Reilly Grant (use Gerrit), 2017-03-15 22:59:12]

The CQ bit was checked by reillyg@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2017-03-15 22:59:37]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[Reilly Grant (use Gerrit), 2017-03-16 00:27:55]

reillyg@chromium.org changed reviewers:
+ mcasas@chromium.org

[Reilly Grant (use Gerrit), 2017-03-16 00:27:56]

Please take a look.

[commit-bot: I haz the power, 2017-03-16 00:39:32]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2017-03-16 00:39:33]

Dry run: This issue passed the CQ dry run.

[mcasas, 2017-03-16 17:00:48]

lgtm with a question.

https://codereview.chromium.org/2751173004/diff/1/third_party/WebKit/Source/m...
File third_party/WebKit/Source/modules/webusb/USB.cpp (right):

https://codereview.chromium.org/2751173004/diff/1/third_party/WebKit/Source/m...
third_party/WebKit/Source/modules/webusb/USB.cpp:227:
ensureDeviceManagerConnection();
Can USB receive connect/disconnect events before 
running either getDevices() or requestDevice(...) ? 
Still, why do we need to connect to the device 
manager here? Wouldn't we do it  anyway during either 
of the two USB.idl operations?

[Reilly Grant (use Gerrit), 2017-03-16 17:43:14]

https://codereview.chromium.org/2751173004/diff/1/third_party/WebKit/Source/m...
File third_party/WebKit/Source/modules/webusb/USB.cpp (right):

https://codereview.chromium.org/2751173004/diff/1/third_party/WebKit/Source/m...
third_party/WebKit/Source/modules/webusb/USB.cpp:227:
ensureDeviceManagerConnection();
On 2017/03/16 17:00:48, mcasas wrote:
> Can USB receive connect/disconnect events before 
> running either getDevices() or requestDevice(...) ? 
> Still, why do we need to connect to the device 
> manager here? Wouldn't we do it  anyway during either 
> of the two USB.idl operations?

Yes. An event will be dispatched whenever a device the script has permission to
access is added or removed. getDevices() returns the current state and
requestDevice() asks for more permissions.

[Reilly Grant (use Gerrit), 2017-03-16 17:43:35]

The CQ bit was checked by reillyg@chromium.org

[commit-bot: I haz the power, 2017-03-16 17:44:17]

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, 2017-03-16 17:51:45]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1489686215966850, "parent_rev":
"321a74e9f93e8f1f02bff86b0b777ae7ba961b37", "commit_rev":
"7f238dd47bf022bc3f40fd64131c5a2784a9da3a"}

[commit-bot: I haz the power, 2017-03-16 17:52:31]

Description was changed from

==========
Make navigator.usb open the DeviceManager connection lazily.

This change makes it so that accessing the navigator.usb object does not
automatically cause Blink to connect to the browser process for an
instance of the DeviceManager service. This is useful because it makes
it easier for tests to register a Mojo service override before the
connection is made.

BUG=None
==========

to

==========
Make navigator.usb open the DeviceManager connection lazily.

This change makes it so that accessing the navigator.usb object does not
automatically cause Blink to connect to the browser process for an
instance of the DeviceManager service. This is useful because it makes
it easier for tests to register a Mojo service override before the
connection is made.

BUG=None

Review-Url: https://codereview.chromium.org/2751173004
Cr-Commit-Position: refs/heads/master@{#457484}
Committed:
https://chromium.googlesource.com/chromium/src/+/7f238dd47bf022bc3f40fd64131c...
==========

[commit-bot: I haz the power, 2017-03-16 17:52:32]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/7f238dd47bf022bc3f40fd64131c...