perf: Enable field trial testing for image animations in cc.

Bug: 735662
Change-Id: I44d121a5109f7c76667630303200ba30329f7341
Reviewed-on: https://chromium-review.googlesource.com/704035Reviewed-by: Steven Holte <holte@chromium.org>
Commit-Queue: Khushal <khushalsagar@chromium.org>
Cr-Commit-Position: refs/heads/master@{#506969}

testing/variations/fieldtrial_testing_config.json

@@ -716,6 +716,25 @@
             ]
         }
     ],
+    "CompositorImageAnimation": [
+        {
+            "platforms": [
+                "android",
+                "chromeos",
+                "linux",
+                "mac",
+                "win"
+            ],
+            "experiments": [
+                {
+                    "name": "CompositorImageAnimation",
+                    "enable_features": [
+                        "CompositorImageAnimation"
+                    ]
+                }
+            ]
+        }
+    ],
     "CopylessPaste": [
         {
             "platforms": [