Turn on Native Window Occlusion on TOT.

Bug: 813093
Change-Id: I9f9bbdd79924ad1de0d48956413b29de4b45cbf5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2424498Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: David Bienvenu <davidbienvenu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#810088}

ui/base/ui_base_features.cc

@@ -15,7 +15,7 @@ namespace features {
 #if defined(OS_WIN)
 // If enabled, calculate native window occlusion - Windows-only.
 const base::Feature kCalculateNativeWinOcclusion{
-    "CalculateNativeWinOcclusion", base::FEATURE_DISABLED_BY_DEFAULT};
+    "CalculateNativeWinOcclusion", base::FEATURE_ENABLED_BY_DEFAULT};
 #endif  // OW_WIN
 
 // Whether or not to delegate color queries to the color provider.