Add testing config for DriveFsBidirectionalNativeMessaging

Bug: 1067346
Change-Id: I32f42a3a4a3c6a1a0d5e24aa013d4610a07fb7bb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2596471
Auto-Submit: Austin Tankiang <austinct@chromium.org>
Reviewed-by: Luciano Pacheco <lucmult@chromium.org>
Commit-Queue: Austin Tankiang <austinct@chromium.org>
Cr-Commit-Position: refs/heads/master@{#840520}

testing/variations/fieldtrial_testing_config.json

@@ -2911,6 +2911,21 @@
             ]
         }
     ],
+    "DriveFsBidirectionalNativeMessaging": [
+        {
+            "platforms": [
+                "chromeos"
+            ],
+            "experiments": [
+                {
+                    "name": "Enabled",
+                    "enable_features": [
+                        "DriveFsBidirectionalNativeMessaging"
+                    ]
+                }
+            ]
+        }
+    ],
     "DynamicTcmallocThreadCache": [
         {
             "platforms": [