Add field trial config for CalculateNativeWinOcclusionCheckVirtualDesktopUsed...

Add field trial config for CalculateNativeWinOcclusionCheckVirtualDesktopUsed since it'll be tested on beta.

Bug: 1162132
Change-Id: I684dee12e2b6034197881ebab5752499c980f525
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2633528Reviewed-by: Robert Kaplow <rkaplow@chromium.org>
Commit-Queue: John Abd-El-Malek <jam@chromium.org>
Cr-Commit-Position: refs/heads/master@{#845248}

testing/variations/fieldtrial_testing_config.json

@@ -1257,6 +1257,21 @@
             ]
         }
     ],
+    "CalculateNativeWinOcclusionCheckVirtualDesktopUsed": [
+        {
+            "platforms": [
+                "windows"
+            ],
+            "experiments": [
+                {
+                    "name": "Enabled",
+                    "enable_features": [
+                        "CalculateNativeWinOcclusionCheckVirtualDesktopUsed"
+                    ]
+                }
+            ]
+        }
+    ],
     "CastMediaRouteProviderAndGlobalMediaControlsForCast": [
         {
             "platforms": [