Fix recently added abort histogram names.

These histograms were added in
https://codereview.chromium.org/2545593003, but the entries in
histograms.xml were incorrect. This change fixes the naming error.

Review-Url: https://codereview.chromium.org/2560103002
Cr-Commit-Position: refs/heads/master@{#437646}

tools/metrics/histograms/histograms.xml

@@ -112362,15 +112362,17 @@ value.
       label="(experimental) Page load that was initiated from the browser
              process"/>
   <affected-histogram
-      name="PageLoad.AbortTiming.ForwardBackNavigation.AfterCommit.BeforePaint"/>
+      name="PageLoad.Experimental.AbortTiming.ForwardBackNavigation.AfterCommit.BeforePaint"/>
   <affected-histogram
-      name="PageLoad.AbortTiming.ForwardBackNavigation.BeforeCommit"/>
+      name="PageLoad.Experimental.AbortTiming.ForwardBackNavigation.BeforeCommit"/>
   <affected-histogram
-      name="PageLoad.AbortTiming.NewNavigation.AfterCommit.BeforePaint"/>
-  <affected-histogram name="PageLoad.AbortTiming.NewNavigation.BeforeCommit"/>
+      name="PageLoad.Experimental.AbortTiming.NewNavigation.AfterCommit.BeforePaint"/>
   <affected-histogram
-      name="PageLoad.AbortTiming.Reload.AfterCommit.BeforePaint"/>
-  <affected-histogram name="PageLoad.AbortTiming.Reload.BeforeCommit"/>
+      name="PageLoad.Experimental.AbortTiming.NewNavigation.BeforeCommit"/>
+  <affected-histogram
+      name="PageLoad.Experimental.AbortTiming.Reload.AfterCommit.BeforePaint"/>
+  <affected-histogram
+      name="PageLoad.Experimental.AbortTiming.Reload.BeforeCommit"/>
 </histogram_suffixes>
 
 <histogram_suffixes name="PageLoadType">