Add OzoneDrmMojo field trial config

Bug: 620927
Change-Id: I3870dd2e6cad2278036dfd484e9410f0bb197572
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1865653Reviewed-by: Ilya Sherman <isherman@chromium.org>
Commit-Queue: Saman Sami <samans@chromium.org>
Cr-Commit-Position: refs/heads/master@{#708831}

testing/variations/fieldtrial_testing_config.json

@@ -4144,6 +4144,21 @@
             ]
         }
     ],
+    "OzoneDrmMojo": [
+        {
+            "platforms": [
+                "chromeos"
+            ],
+            "experiments": [
+                {
+                    "name": "OzoneDrmMojo",
+                    "enable_features": [
+                        "OzoneDrmMojo"
+                    ]
+                }
+            ]
+        }
+    ],
     "PDFClickToOpen": [
         {
             "platforms": [