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The motivation is to allow classes to be exported (for component builds) so that
a browser test can be written outside of device/ and on top
of content/ and the needed classes can be used to write a fake/mock
provider with fake/mock sensors (the test will come in follow up CL).
The motivation is to test end to end the feature in a cross platform
and non hardware dependent way and checking JavaScript behavior.

BUG=606766

Review-Url: https://chromiumcodereview.appspot.com/2431163004
Cr-Commit-Position: refs/heads/master@{#426567}