Merge b321e4f568 and e8fa00efd0 into M-39 branch (issue 418207).

Use IOService enumeration instead of IOHIDManager in HidServiceMac.

Using the IOServiceAddMatchingNotification API to monitor devices
connected to the system is preferable to IOHIDManager because it is
lighter weight. IOHIDManager forces its own lifetime expectations on
the IOHIDDevice objects that it creates and opens all devices it sees
for I/O whether or not there is a Chrome app that is using them.

As a necessary step to simplify this transition the device/hid API now
lives on the browser UI thread when running on OS X. This change will
soon be made for Linux and Windows as well. This change should also
reduce the risk of race conditions as observed in bug 418207 which is
why it is being made independently of the other platforms.

BUG=418207,413978
R=rockot@chromium.org, rpaquay@chromium.org, thestig@chromium.org

Review URL: https://codereview.chromium.org/637863003

Cr-Commit-Position: refs/heads/master@{#298793}

Conflicts:
	extensions/browser/api/hid/hid_api.cc

Add HidConnection::Close and register OS X callbacks on the UI thread.

The platform implementation of a HID connection may need to cancel I/O
operations when the connection is closed. If this is done during the
object destructor then any pointers held by those pending operations are
immediately invalid. A separate Close method allows the cleanup to
happen while the object is still available to handle asynchronous
cancellation events.

The OS X implementation will take advantage of this immediately to
register and unregister its input report callback from the UI thread to
avoid a race between event delivery and object cleanup. I've added
comments explaining why not all operations on the IOHIDDevice object
could be moved to the UI thread.

BUG=418207

Review URL: https://codereview.chromium.org/615633008

Cr-Commit-Position: refs/heads/master@{#298384}

Conflicts:
	device/hid/hid_connection_linux.h
	device/hid/hid_connection_mac.h
	device/hid/hid_connection_win.h

Review URL: https://codereview.chromium.org/648613002

Cr-Commit-Position: refs/branch-heads/2171@{#188}
Cr-Branched-From: 267aeeb8d85c8503a7fd12bd14654b8ea78d3974-refs/heads/master@{#297060}

0 files changed, 0 insertions, 0 deletions