The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/f3b97b64f2b753ace84984f25d6907663ce0d966

commit f3b97b64f2b753ace84984f25d6907663ce0d966
Author: Julien Isorce <julien.isorce@chromium.org>
Date: Thu Oct 25 17:36:45 2018

Disable fetching thumbnails if thumbnailSize is 0 in NativeDesktopMediaList

Capturing window thmubnails is expensive as it actually uses a
desktop capturer and it records one full frame per screen or window.
Then it downscales to the default size 100x100. No need all of this
when the app is only interested in have a list of the sources.
So skip this processing when the thumbnail size is empty.

This CL also adds a new unit test NativeDesktopMediaListTest.EmptyThumbnail
which fails without this patch.

Bug:  898319 
Test: ./out/debug/unit_tests --gtest_filter=*NativeDesktopMediaListTest.EmptyThumbnail*

Change-Id: I2ff56c7bcbaf277813b1a990a77bc9807a07a91e
Reviewed-on: https://chromium-review.googlesource.com/c/1295111
Commit-Queue: Weiyong Yao <braveyao@chromium.org>
Reviewed-by: Weiyong Yao <braveyao@chromium.org>
Cr-Commit-Position: refs/heads/master@{#602775}
[modify] https://crrev.com/f3b97b64f2b753ace84984f25d6907663ce0d966/chrome/browser/media/webrtc/native_desktop_media_list.cc
[modify] https://crrev.com/f3b97b64f2b753ace84984f25d6907663ce0d966/chrome/browser/media/webrtc/native_desktop_media_list_unittest.cc