Enable GpuWatchdogV2 in Field trial testing for all platforms

Bug: 949839
Change-Id: I5939069144719c501209af3cda3b7693f61f8866
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1682315
Commit-Queue: Maggie Chen <magchen@chromium.org>
Reviewed-by: Ilya Sherman <isherman@chromium.org>
Reviewed-by: Zhenyao Mo <zmo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#688375}

testing/variations/fieldtrial_testing_config.json

@@ -2546,6 +2546,25 @@
             ]
         }
     ],
+    "GpuWatchdogV2": [
+        {
+            "platforms": [
+                "android",
+                "chromeos",
+                "linux",
+                "mac",
+                "windows"
+            ],
+            "experiments": [
+                {
+                    "name": "Enabled",
+                    "enable_features": [
+                        "GpuWatchdogV2"
+                    ]
+                }
+            ]
+        }
+    ],
     "GridLayoutForNtpShortcuts": [
         {
             "platforms": [