Add PermissionChip feature to fieldtrial_testing_config.json.

As a prerequisite to landing cr/339683181.

Bug: 1134294
Change-Id: I95a0774957c5ba1cae28faad5916865f50e5a8d7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2510054
Commit-Queue: Bret Sepulveda <bsep@chromium.org>
Reviewed-by: Brian White <bcwhite@chromium.org>
Cr-Commit-Position: refs/heads/master@{#829185}

testing/variations/fieldtrial_testing_config.json

@@ -5350,6 +5350,24 @@
             ]
         }
     ],
+    "PermissionChip": [
+        {
+            "platforms": [
+                "chromeos",
+                "linux",
+                "mac",
+                "windows"
+            ],
+            "experiments": [
+                {
+                    "name": "Enabled",
+                    "enable_features": [
+                        "PermissionChip"
+                    ]
+                }
+            ]
+        }
+    ],
     "PermissionPromptUICocoa": [
         {
             "platforms": [