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```yaml
IN CASE OF PROBLEMS: If this CL causes your site/app to break, you are
using deprecated features that have now been removed. Please see [2] to
enroll in the Deprecation Extension program to give yourself more time.
```

With this CL, the HTML Imports Web Components v0 API is disabled by
default. The other two Web Components v0 APIs were already disabled
by another CL ([4]).

These features were deprecated in August, 2018, in [1]. The original
removal timeline called for a deadline of M73. Due to high use counters
for the features, this deadline was extended to M80, which is now here.
For those sites that need additional time, there is a "deprecation
extension" (sometimes called a "reverse origin trial") that can be used
to extend this removal for specific sites through M87. For more
information on that, see [2]. For overall context on this removal,
including motivation and ways to test/upgrade, see [3].

With this CL, these features will still be enabled for testing across
all test suites. Once this CL has had a chance to land and stabilize,
subsequent CLs will disable the features for all tests by default, and
enable a virtual test suite to continue testing specific code with WCv0
features enabled, to ensure the features continue to function through
the end of the deprecation extension period.

Note that this CL re-enables all three Web Components v0 APIs on Android
Webview, due to lingering issues with origin trial support. See
crbug.com/1021631 for more information. See https://crbug.com/1020737
for why all three APIs are being re-enabled.

[1] https://groups.google.com/a/chromium.org/forum/#!msg/blink-dev/h-JwMiPUnuU/sl79aLoLBQAJ
[2] https://developers.chrome.com/origintrials/#/view_trial/2431943798780067841
[3] https://developers.google.com/web/updates/2019/07/web-components-time-to-upgrade
[4] https://chromium.googlesource.com/chromium/src/+/f52dff0d3c5bc52ba608920f843162832f2da6b1

Bug: 911943, 1021631, 1020737
Change-Id: I0df0898674cfec7c0db50ada9900a9a4027eb226
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1869562
Commit-Queue: Mason Freed <masonfreed@chromium.org>
Reviewed-by: Sam McNally <sammc@chromium.org>
Reviewed-by: Luciano Pacheco <lucmult@chromium.org>
Reviewed-by: Darin Fisher <darin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#713537}