Implement DeviceMotionEvent API

Update SensorManagerChromeOS to implement the DeviceMotionEvent API. Begin
processing accelerometer events into device motion events.

Updated all previous unittests of orientations to also verify the according
device motion events.

TEST=SensorManagerChromeOSTest.MotionBuffer,
SensorManagerChromeOSTest.GravityFilterCompletesForStationaryDevice,
SensorManagerChromeOSTest.NonGravityAcceleration,
SensorManagerChromeOSTest.AccelerationAgainstGravity
BUG=427662

Review URL: https://codereview.chromium.org/934843002

Cr-Commit-Position: refs/heads/master@{#320159}
14 files changed