Implement most of WebUSB device client interface

Implement most of WebUSB device client interface

This wires up the WebUSB device client interface from content/renderer
to the devices app. Bulk and interrupt transfer support remains
unimplemented, pending changes to the underlying service interface.

BUG=492204
R=reillyg@chromium.org

Committed: https://crrev.com/3a5e7bccbe7dc0e6c58ebb60e840d13794ce5a7b
Cr-Commit-Position: refs/heads/master@{#345208}

[Ken Rockot(use gerrit already), 2015-08-24 20:19:54]

please take a look!

[Reilly Grant (use Gerrit), 2015-08-24 21:24:15]

This patch should be updated to match the details I've added to the spec
recently but it lgtm for now.

https://codereview.chromium.org/1314493003/diff/1/content/renderer/usb/web_us...
File content/renderer/usb/web_usb_device_impl.cc (right):

https://codereview.chromium.org/1314493003/diff/1/content/renderer/usb/web_us...
content/renderer/usb/web_usb_device_impl.cc:121:
scoped_ptr<blink::WebUSBTransferInfo> info(new blink::WebUSBTransferInfo);
It shouldn't matter in this case but calling constructors without parenthesis
makes me nervous.

https://codereview.chromium.org/1314493003/diff/1/content/renderer/usb/web_us...
content/renderer/usb/web_usb_device_impl.cc:124: data.Swap(&bytes);
What's the reason for swapping here? It seems like WebVector::assign will work
on a mojo::Array.

[Ken Rockot(use gerrit already), 2015-08-24 21:51:07]

https://codereview.chromium.org/1314493003/diff/1/content/renderer/usb/web_us...
File content/renderer/usb/web_usb_device_impl.cc (right):

https://codereview.chromium.org/1314493003/diff/1/content/renderer/usb/web_us...
content/renderer/usb/web_usb_device_impl.cc:121:
scoped_ptr<blink::WebUSBTransferInfo> info(new blink::WebUSBTransferInfo);
On 2015/08/24 21:24:15, Reilly Grant wrote:
> It shouldn't matter in this case but calling constructors without parenthesis
> makes me nervous.

Fair enough. I don't really see a problem with it either way, so I changed it.

https://codereview.chromium.org/1314493003/diff/1/content/renderer/usb/web_us...
content/renderer/usb/web_usb_device_impl.cc:124: data.Swap(&bytes);
On 2015/08/24 21:24:15, Reilly Grant wrote:
> What's the reason for swapping here? It seems like WebVector::assign will work
> on a mojo::Array.

Oops, you're right. Done.

[Ken Rockot(use gerrit already), 2015-08-24 22:53:47]

The CQ bit was checked by rockot@chromium.org

[Ken Rockot(use gerrit already), 2015-08-24 22:53:47]

The patchset sent to the CQ was uploaded after l-g-t-m from reillyg@chromium.org
Link to the patchset: https://codereview.chromium.org/1314493003/#ps40001
(title: "allow null data on controlTransfer")

[commit-bot: I haz the power, 2015-08-24 22:54:02]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1314493003/40001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1314493003/40001

[commit-bot: I haz the power, 2015-08-24 23:39:40]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2015-08-24 23:40:56]

Patchset 3 (id:??) landed as
https://crrev.com/3a5e7bccbe7dc0e6c58ebb60e840d13794ce5a7b
Cr-Commit-Position: refs/heads/master@{#345208}