InspectRarContent: Enable testing on bots for Desktop platforms

See also: http://cl/235019478

Bug: 909778
Change-Id: I1082d8c4f81c27ab62840ed78196db9cb71c8b3e
Reviewed-on: https://chromium-review.googlesource.com/c/1481602Reviewed-by: Daniel Rubery <drubery@chromium.org>
Reviewed-by: Mark Pearson <mpearson@chromium.org>
Commit-Queue: Varun Khaneja <vakh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#635205}

testing/variations/fieldtrial_testing_config.json

@@ -2320,6 +2320,24 @@
             ]
         }
     ],
+    "InspectRarContent": [
+        {
+            "platforms": [
+                "chromeos",
+                "linux",
+                "mac",
+                "windows"
+            ],
+            "experiments": [
+                {
+                    "name": "Enabled",
+                    "enable_features": [
+                        "InspectRarContent"
+                    ]
+                }
+            ]
+        }
+    ],
     "InstanceID": [
         {
             "platforms": [