Enable Device Motion API on all platforms by default.

After this change the JavaScript expression 'window.DeviceMotionEvent'
will start evaluating to true on all platforms.

For Android, Windows and Mac devices with accelerometer and
gyroscope sensors events will start being delivered.
For devices without such sensors, and for other platforms
(e.g. Chrome OS, Linux) which do not have corresponding sensor
data fetcher implementations, we'll deliver a one-shot event
with all properties set the NULL, per the specification.

This patch also removes the obsolete 'enable-device-motion'
flag, instead the 'disable-device-motion' flag is available.

BUG=135804

Review URL: https://chromiumcodereview.appspot.com/24220002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@224164 0039d316-1c4b-4281-b951-d872f2087c98
6 files changed