Adding fieldtrial testing for IndexedDBHighPriority

Bug: 1014313
Change-Id: I21f170d67f92a3514040d2f8fb3315c0770379ee
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1894254
Auto-Submit: Daniel Murphy <dmurph@chromium.org>
Commit-Queue: Brian White <bcwhite@chromium.org>
Reviewed-by: Brian White <bcwhite@chromium.org>
Cr-Commit-Position: refs/heads/master@{#711915}

testing/variations/fieldtrial_testing_config.json

@@ -3024,6 +3024,31 @@
             ]
         }
     ],
+    "IndexedDBHighPriority": [
+        {
+            "platforms": [
+                "android",
+                "chromeos",
+                "linux",
+                "mac",
+                "windows"
+            ],
+            "experiments": [
+                {
+                    "name": "Enabled",
+                    "enable_features": [
+                        "HighPriorityDatabaseTaskType"
+                    ]
+                },
+                {
+                    "name": "Control",
+                    "disable_features": [
+                        "HighPriorityDatabaseTaskType"
+                    ]
+                }
+            ]
+        }
+    ],
     "InspectRarContent": [
         {
             "platforms": [