Revert "feat(HighContrast): Expose the XAML HighContrastChanged event to JS"

[rozele]

Reverts #1443

[rozele]

@antonkh this is currently broken in master, please rebase and fix this work. cc @rigdern

[codecov-io]

Codecov Report

Merging #1473 into master will decrease coverage by 0.61%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1473      +/-   ##
==========================================
- Coverage   31.47%   30.86%   -0.62%     
==========================================
  Files         266      267       +1     
  Lines       19296    19697     +401     
  Branches     1613     1716     +103     
==========================================
+ Hits         6073     6079       +6     
- Misses      13072    13466     +394     
- Partials      151      152       +1

Impacted Files	Coverage Δ
...tNative.Shared/Modules/Network/NetworkingModule.cs	68.08% <0%> (-0.36%)	⬇️
ReactWindows/ReactNative.Shared/ReactRootView.cs	0% <0%> (ø)	⬆️
...ive.Shared/DevSupport/DisabledDevSupportManager.cs	0% <0%> (ø)	⬆️
...Windows/ReactNative.Shared/Bridge/ReactInstance.cs	0% <0%> (ø)	⬆️
...s/ReactNative.Shared/DevSupport/DevServerHelper.cs	0% <0%> (ø)	⬆️
...eactNative.Shared/Bridge/JavaScriptBundleLoader.cs	0% <0%> (ø)	⬆️
ReactWindows/ReactNative.Net46/ReactPage.cs	0% <0%> (ø)	⬆️
...tNative.Shared/ReactContextInitializedEventArgs.cs	0% <0%> (ø)
...ReactNative.Shared/DevSupport/DevSupportManager.cs	0.19% <0%> (+0.19%)	⬆️
...Windows/ReactNative.Shared/ReactInstanceManager.cs	1.01% <0%> (+1.01%)	⬆️

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[antonkh]

What is broken? I'm testing it with S4L which is based on a slightly outdated (v0.46.0) fork of RNW.

[antonkh]

I think I've found the problem you meant: in the Playground app I get an "Element not found" exception with a callstack referring to add_HighContrastChanged

[antonkh]

Looks like in case of the playground app the event subscription happens on a wrong thread. I fixed it this way:

        public override void Initialize()
        {
            DispatcherHelpers.RunOnDispatcher(() =>
            {
                _accessibility.HighContrastChanged += OnHighContrastChanged;
            });
        }

It's not clear to me why in S4L it doesn't cause an exception.

[rozele]

Ah, right, I think we updated so that Initialize and OnReactInstanceDispose run on the native module queue thread.

[antonkh]

I've sent a PR to fix this: #1476

[rozele]

Will close this and merge #1476