Disable event source in mobile sample apps

[vitek-karas]

Event source support is disabled by default by the iOS and Android SDKs, and ideally the sample app should match that behavior as closely as possible in general runtime functionality.

The sample app is also used to measure app size, and so it should be representative of the defaults users will get when using SDK.

[dotnet-policy-service]

Tagging subscribers to 'arch-android': @vitek-karas, @simonrozsival, @steveisok, @akoeplinger
See info in area-owners.md if you want to be subscribed.

[akoeplinger]

We already have this code which sets the ~same default for testing:

runtime/eng/testing/tests.mobile.targets

Lines 34 to 40 in f402418

	<!-- Reduce library test app size by trimming framework library features -->
	<DebuggerSupport Condition="'$(DebuggerSupport)' == '' and '$(Configuration)' != 'Debug'">false</DebuggerSupport>
	<EnableUnsafeUTF7Encoding Condition="'$(EnableUnsafeUTF7Encoding)' == ''">false</EnableUnsafeUTF7Encoding>
	<EventSourceSupport Condition="'$(EventSourceSupport)' == ''">false</EventSourceSupport>
	<HttpActivityPropagationSupport Condition="'$(HttpActivityPropagationSupport)' == ''">false</HttpActivityPropagationSupport>
	<UseSystemResourceKeys Condition="'$(UseSystemResourceKeys)' == ''">false</UseSystemResourceKeys>
	<UseNativeHttpHandler Condition="'$(UseNativeHttpHandler)' == ''">false</UseNativeHttpHandler>

Would be nice to move this to extract this into a common .targets that we can import into the samples apps.
Browser/wasm sample apps have the same issue.

[matouskozak]

We already have this code which sets the ~same default for testing:

runtime/eng/testing/tests.mobile.targets

Lines 34 to 40 in f402418

	<!-- Reduce library test app size by trimming framework library features -->
	<DebuggerSupport Condition="'$(DebuggerSupport)' == '' and '$(Configuration)' != 'Debug'">false</DebuggerSupport>
	<EnableUnsafeUTF7Encoding Condition="'$(EnableUnsafeUTF7Encoding)' == ''">false</EnableUnsafeUTF7Encoding>
	<EventSourceSupport Condition="'$(EventSourceSupport)' == ''">false</EventSourceSupport>
	<HttpActivityPropagationSupport Condition="'$(HttpActivityPropagationSupport)' == ''">false</HttpActivityPropagationSupport>
	<UseSystemResourceKeys Condition="'$(UseSystemResourceKeys)' == ''">false</UseSystemResourceKeys>
	<UseNativeHttpHandler Condition="'$(UseNativeHttpHandler)' == ''">false</UseNativeHttpHandler>

Would be nice to move this to extract this into a common .targets that we can import into the samples apps. Browser/wasm sample apps have the same issue.

What kind of feature switches would Browser/wasm sample apps want to turn off/on?

For mobile sample apps, I think it would make sense to set an intersection of Android https://github.com/dotnet/android/blob/119d46c3a424ffeb3721718043616bfb10f5622f/src/Xamarin.Android.Build.Tasks/Microsoft.Android.Sdk/targets/Microsoft.Android.Sdk.DefaultProperties.targets#L109-L120 and macios https://github.com/xamarin/xamarin-macios/blob/92092f67fdc0979b9db95bdef55a9c8280d383e4/dotnet/targets/Xamarin.Shared.Sdk.targets#L121-L136 settings.

E.g.:

<EnableUnsafeBinaryFormatterSerialization Condition="'$(EnableUnsafeBinaryFormatterSerialization)' == ''">false</EnableUnsafeBinaryFormatterSerialization>
<EnableUnsafeUTF7Encoding Condition="'$(EnableUnsafeUTF7Encoding)' == ''">false</EnableUnsafeUTF7Encoding>
<EventSourceSupport Condition="'$(EventSourceSupport)' == ''">false</EventSourceSupport>
<HttpActivityPropagationSupport Condition="'$(HttpActivityPropagationSupport)' == ''">false</HttpActivityPropagationSupport>
<InvariantGlobalization Condition="'$(InvariantGlobalization)' == ''">false</InvariantGlobalization>
<StartupHookSupport Condition="'$(StartupHookSupport)' == ''">false</StartupHookSupport>
<UseNativeHttpHandler Condition="'$(UseNativeHttpHandler)' == ''">true</UseNativeHttpHandler>

[ivanpovazan]

I agree with @akoeplinger
Probably we can make use of this file: https://github.com/dotnet/runtime/blob/main/src/mono/msbuild/common/CommonMobileBuild.props