[Image Capture] Add focusDistance constraint. This CL adds focusDistance to ImageCapture API. This was added to the spec in https://github.com/w3c/mediacapture-image/pull/175 Layout tests and mock tests are updated to support the same. Support for Android is added. TEST= run the demo in https://codepen.io/rijuB/pen/NzWpxG use slider to change focusDistance. BUG=732807 Intent to Implement and Ship discussions: https://groups.google.com/a/chromium.org/forum/#!topic/blink-dev/oNxzXaFY9c8 Change-Id: I9b7cbf3c85fd35741a8c7ed229910a996e14ee8f Reviewed-on: https://chromium-review.googlesource.com/1124839 Reviewed-by: Miguel Casas <mcasas@chromium.org> Reviewed-by: Kinuko Yasuda <kinuko@chromium.org> Reviewed-by: Guido Urdaneta <guidou@chromium.org> Commit-Queue: Rijubrata Bhaumik <rijubrata.bhaumik@intel.com> Cr-Commit-Position: refs/heads/master@{#588299} 
diff --git a/mediacapture-image/MediaStreamTrack-getCapabilities.html b/mediacapture-image/MediaStreamTrack-getCapabilities.html index 452b223..eceaf5b 100644 --- a/mediacapture-image/MediaStreamTrack-getCapabilities.html +++ b/mediacapture-image/MediaStreamTrack-getCapabilities.html 
@@ -124,6 +124,14 @@  assert_equals(capabilities.sharpness.step,  mockCapabilities.sharpness.step);   + assert_true(capabilities.focusDistance instanceof MediaSettingsRange); + assert_equals(capabilities.focusDistance.max, + mockCapabilities.focusDistance.max); + assert_equals(capabilities.focusDistance.min, + mockCapabilities.focusDistance.min); + assert_equals(capabilities.focusDistance.step, + mockCapabilities.focusDistance.step); +  assert_true(capabilities.zoom instanceof MediaSettingsRange);  assert_equals(capabilities.zoom.max, mockCapabilities.zoom.max);  assert_equals(capabilities.zoom.min, mockCapabilities.zoom.min);