arc: Add declaration of ArcUseHighMemoryDalvikProfile finch experiment

As above

BUG=1164478
TEST=None

Change-Id: I36de164195bc99ae0d760db9ce093df9c1bce233
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2618583Reviewed-by: Yusuke Sato <yusukes@chromium.org>
Commit-Queue: Yury Khmel <khmel@chromium.org>
Auto-Submit: Yury Khmel <khmel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#841741}

testing/variations/fieldtrial_testing_config.json

@@ -620,6 +620,21 @@
             ]
         }
     ],
+    "ArcUseHighMemoryDalvikProfile": [
+        {
+            "platforms": [
+                "chromeos"
+            ],
+            "experiments": [
+                {
+                    "name": "Enabled",
+                    "enable_features": [
+                        "ArcUseHighMemoryDalvikProfile"
+                    ]
+                }
+            ]
+        }
+    ],
     "AssistAutocorrect": [
         {
             "platforms": [