Remove XRSessionDeviceConfig.uses_input_eventing and related code (we…

…b-platform-tests#40530)

This commit removes the uses_input_eventing_ variable from the
XRSessionDeviceConfig interface and all the code that relied on it.
The XRSessionDeviceConfig.uses_input_eventing feature was originally
added to support WMR but is no longer needed since no runtimes support
it now.

Bug: 1429644
Change-Id: I6d691f67e20d5f430169556b215e038c6b1c3173
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4604546
Quick-Run: Alexander Cooper <alcooper@chromium.org>
Reviewed-by: Alex Gough <ajgo@chromium.org>
Reviewed-by: Alexander Cooper <alcooper@chromium.org>
Commit-Queue: Alexander Cooper <alcooper@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1157619}

Co-authored-by: Mahmoud Ahmed <mahmoudaahmedd@gmail.com>

resources/chromium/webxr-test.js

@@ -985,8 +985,6 @@ class MockRuntime {
         environmentProviderRequest.handle);
   }
 
-  setInputSourceButtonListener(listener) { listener.$.close(); }
-
   // XREnvironmentIntegrationProvider implementation:
   subscribeToHitTest(nativeOriginInformation, entityTypes, ray) {
     if (!this.supportedModes_.includes(xrSessionMojom.XRSessionMode.kImmersiveAr)) {
@@ -1212,7 +1210,6 @@ class MockRuntime {
             clientReceiver: clientReceiver,
             enabledFeatures: enabled_features,
             deviceConfig: {
-              usesInputEventing: false,
               defaultFramebufferScale: this.defaultFramebufferScale_,
               supportsViewportScaling: true,
               depthConfiguration: