Adds fieldtrial testing config for WebRTC-VP8-Postproc-Config

Bug: webrtc:11551, b/163310303
Change-Id: I5eb5f59f9c68315305c1bdb380bb7d3d192a02c2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2487340
Auto-Submit: Erik Språng <sprang@chromium.org>
Commit-Queue: Mark Pearson <mpearson@chromium.org>
Reviewed-by: Mark Pearson <mpearson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#819162}

testing/variations/fieldtrial_testing_config.json

@@ -7836,6 +7836,24 @@
             ]
         }
     ],
+    "WebRTC-VP8-Postproc-Config": [
+        {
+            "platforms": [
+                "windows",
+                "mac",
+                "chromeos",
+                "linux",
+                "android",
+                "android_weblayer",
+                "android_webview"
+            ],
+            "experiments": [
+                {
+                    "name": "Enabled-8,30,60"
+                }
+            ]
+        }
+    ],
     "WebRTC-VP8ConferenceTemporalLayers": [
         {
             "platforms": [