Delay WebUSB initialization until after browser startup.

Delay WebUSB initialization until after browser startup.

Initializing the WebUSB device detector module causes the USB service to
be initialized and enumerate all USB device connected to the system.
This can cause unnecessary delay during browser startup. The purpose of
this module is to detect devices connected after Chrome starts to
display a notification so it doesn't matter if it is initialized after
first page load.

An UMA histogram for the time spent initializing the detector is also
added to aid further investigation of this issue.

BUG=642107
Review-Url: https://codereview.chromium.org/2295023002
Cr-Commit-Position: refs/heads/master@{#415971}
(cherry picked from commit 478a62181383d2cc7fa545ee6a7a91ab34fec477)

Committed: https://chromium.googlesource.com/chromium/src/+/165965c08079b64a645819ffddc221915891409f

[Reilly Grant (use Gerrit), 2016-09-02 18:28:55]

Description was changed from

==========
Delay WebUSB initialization until after browser startup.

Initializing the WebUSB device detector module causes the USB service to
be initialized and enumerate all USB device connected to the system.
This can cause unnecessary delay during browser startup. The purpose of
this module is to detect devices connected after Chrome starts to
display a notification so it doesn't matter if it is initialized after
first page load.

An UMA histogram for the time spent initializing the detector is also
added to aid further investigation of this issue.

BUG=642107

Review-Url: https://codereview.chromium.org/2295023002
Cr-Commit-Position: refs/heads/master@{#415971}
(cherry picked from commit 478a62181383d2cc7fa545ee6a7a91ab34fec477)
==========

to

==========
Delay WebUSB initialization until after browser startup.

Initializing the WebUSB device detector module causes the USB service to
be initialized and enumerate all USB device connected to the system.
This can cause unnecessary delay during browser startup. The purpose of
this module is to detect devices connected after Chrome starts to
display a notification so it doesn't matter if it is initialized after
first page load.

An UMA histogram for the time spent initializing the detector is also
added to aid further investigation of this issue.

BUG=642107

Review-Url: https://codereview.chromium.org/2295023002
Cr-Commit-Position: refs/heads/master@{#415971}
(cherry picked from commit 478a62181383d2cc7fa545ee6a7a91ab34fec477)

Committed:
https://chromium.googlesource.com/chromium/src/+/165965c08079b64a645819ffddc2...
==========

[Reilly Grant (use Gerrit), 2016-09-02 18:28:56]

Committed patchset #1 (id:1) manually as
165965c08079b64a645819ffddc221915891409f.