Add SharedClipboard to fieldtrial_testing_config.json

Bug: 991520
Change-Id: Ibc8f641bff2dde0d675be237a2f3aa6fced81c98
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1808839Reviewed-by: Steven Holte <holte@chromium.org>
Commit-Queue: Michael van Ouwerkerk <mvanouwerkerk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#697526}

testing/variations/fieldtrial_testing_config.json

@@ -5460,6 +5460,25 @@
             ]
         }
     ],
+    "SharedClipboard": [
+        {
+            "platforms": [
+                "android",
+                "chromeos",
+                "linux",
+                "mac",
+                "windows"
+            ],
+            "experiments": [
+                {
+                    "name": "Enabled",
+                    "enable_features": [
+                        "SharedClipboardUI"
+                    ]
+                }
+            ]
+        }
+    ],
     "Show109ObsoleteInfobar": [
         {
             "platforms": [