Add fieldtrial config for WebViewZeroCopyVideo.

Bug: 1091945
Change-Id: I9c7227fcaa0e74c92194fc4c5b5a785d4e6b42ba
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2456632Reviewed-by: Ilya Sherman <isherman@chromium.org>
Commit-Queue: vikas soni <vikassoni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#814974}

testing/variations/fieldtrial_testing_config.json

@@ -7751,6 +7751,21 @@
             ]
         }
     ],
+    "WebViewZeroCopyVideo": [
+        {
+            "platforms": [
+                "android_webview"
+            ],
+            "experiments": [
+                {
+                    "name": "Enabled",
+                    "enable_features": [
+                        "WebViewZeroCopyVideo"
+                    ]
+                }
+            ]
+        }
+    ],
     "WellKnownChangePassword": [
         {
             "platforms": [