Media Capture Depth Stream Extensions API: focal length and depth range.

Under experimental MediaCaptureDepth feature, implements [1]:

partial dictionary MediaTrackSettings {
    double depthNear;
    double depthFar;
    double focalLengthX;
    double focalLengthY;
};

This patch adds the support for it to fake capture device only.

[1]
https://w3c.github.io/mediacapture-depth/#mediatracksettings-dictionary

BUG=616098

Review-Url: https://codereview.chromium.org/2606983002
Cr-Commit-Position: refs/heads/master@{#448567}
23 files changed