predictors: Fix incorrect histogram name.

chrome/browser/page_load_metrics/observers/resource_prefetch_predictor_page_load_metrics_observer.cc

Index: chrome/browser/page_load_metrics/observers/resource_prefetch_predictor_page_load_metrics_observer.cc
diff --git a/chrome/browser/page_load_metrics/observers/resource_prefetch_predictor_page_load_metrics_observer.cc b/chrome/browser/page_load_metrics/observers/resource_prefetch_predictor_page_load_metrics_observer.cc
index 34762b326a29f98b4a62d0e4f2f10681a9c60b01..f5c066eb3b75fe5ca25a831174f057c05572ac81 100644
--- a/chrome/browser/page_load_metrics/observers/resource_prefetch_predictor_page_load_metrics_observer.cc
+++ b/chrome/browser/page_load_metrics/observers/resource_prefetch_predictor_page_load_metrics_observer.cc
@@ -16,7 +16,7 @@ const char kHistogramResourcePrefetchPredictorFirstContentfulPaint[] =
     "PageLoad.Clients.ResourcePrefetchPredictor.PaintTiming."
     "NavigationToFirstContentfulPaint.Prefetchable";
 const char kHistogramResourcePrefetchPredictorFirstMeaningfulPaint[] =
-    "PageLoad.Clients.ResourcePrefetchPredictor.PaintTiming."
+    "PageLoad.Clients.ResourcePrefetchPredictor.Experimental.PaintTiming."
     "NavigationToFirstMeaningfulPaint.Prefetchable";
 
 }  // namespace internal