gpu: Enable new presentation feedback path on waterfall

Bug: 892874
Change-Id: I15a63a95302d8cf55935f1287d4e9b8fb458ada5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1747070Reviewed-by: Ilya Sherman <isherman@chromium.org>
Commit-Queue: Sunny Sachanandani <sunnyps@chromium.org>
Cr-Commit-Position: refs/heads/master@{#686613}

testing/variations/fieldtrial_testing_config.json

@@ -1866,7 +1866,8 @@
                 {
                     "name": "Enabled",
                     "enable_features": [
-                        "DirectCompositionGpuVSync"
+                        "DirectCompositionGpuVSync",
+                        "DirectCompositionPresentationFeedback"
                     ]
                 }
             ]