[VizHitTesting] Enable V2 by default on ChromeOS

The feature has been run on stable(1%) for a while and the metrics are
as expected [1]. Turning it on by default before pushing it to 100%.
[1] https://bugs.chromium.org/p/chromium/issues/detail?id=874919#c48

Bug: 874919
Change-Id: Ibda3b3e280b92b80cd3281478482bd6942a348ee
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1928895Reviewed-by: Robert Kroeger <rjkroege@chromium.org>
Reviewed-by: Steven Holte <holte@chromium.org>
Commit-Queue: Yi Gu <yigu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#718116}

components/viz/common/features.cc

@@ -17,13 +17,8 @@ namespace features {
 const base::Feature kVizDisplayCompositor{"VizDisplayCompositor",
                                           base::FEATURE_ENABLED_BY_DEFAULT};
 
-#if defined(OS_CHROMEOS)
-const base::Feature kEnableVizHitTestSurfaceLayer{
-    "VizHitTestSurfaceLayer", base::FEATURE_DISABLED_BY_DEFAULT};
-#else
 const base::Feature kEnableVizHitTestSurfaceLayer{
     "VizHitTestSurfaceLayer", base::FEATURE_ENABLED_BY_DEFAULT};
-#endif
 
 // Use Skia's readback API instead of GLRendererCopier.
 const base::Feature kUseSkiaForGLReadback{"UseSkiaForGLReadback",

testing/variations/fieldtrial_testing_config.json

@@ -7175,21 +7175,6 @@
             ]
         }
     ],
-    "VizHitTest": [
-        {
-            "platforms": [
-                "chromeos"
-            ],
-            "experiments": [
-                {
-                    "name": "VizHitTestSurfaceLayer",
-                    "enable_features": [
-                        "VizHitTestSurfaceLayer"
-                    ]
-                }
-            ]
-        }
-    ],
     "WKHTTPSystemCookieStore": [
         {
             "platforms": [