Rename to WebViewFileMetricsProviderMetadata

Rename EnabledOnFileMetrics to EnabledOnFileMetrics to match
the finch configuration.

Bug: 1076549
Change-Id: Icabaaec29c29966416bd405a21d9a8de17221bda
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2529235
Commit-Queue: Michael Bai <michaelbai@chromium.org>
Reviewed-by: Alexei Svitkine <asvitkine@chromium.org>
Cr-Commit-Position: refs/heads/master@{#826544}

testing/variations/fieldtrial_testing_config.json

@@ -5362,26 +5362,6 @@
             ]
         }
     ],
-    "PersistentHistogramsFileMetrics": [
-        {
-            "platforms": [
-                "android_webview"
-            ],
-            "experiments": [
-                {
-                    "name": "EnabledOnFileMetrics",
-                    "params": {
-                        "prev_run_metrics_count_only": "true",
-                        "send_unreported_metrics": "yes",
-                        "storage": "MappedFile"
-                    },
-                    "enable_features": [
-                        "PersistentHistograms"
-                    ]
-                }
-            ]
-        }
-    ],
     "PreconnectOnDidFinishNavigation": [
         {
             "platforms": [
@@ -7918,6 +7898,26 @@
             ]
         }
     ],
+    "WebViewFileMetricsProviderMetadata": [
+        {
+            "platforms": [
+                "android_webview"
+            ],
+            "experiments": [
+                {
+                    "name": "Enabled_10",
+                    "params": {
+                        "prev_run_metrics_count_only": "true",
+                        "send_unreported_metrics": "yes",
+                        "storage": "MappedFile"
+                    },
+                    "enable_features": [
+                        "PersistentHistograms"
+                    ]
+                }
+            ]
+        }
+    ],
     "WebViewZeroCopyVideo": [
         {
             "platforms": [