[Offline Pages] Adds classification of some prerender FinalStatus codes as canceled operations or a…

tools/metrics/histograms/histograms.xml

Index: tools/metrics/histograms/histograms.xml
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index 914824063dd1c0a77e82b5c0e100b018494220a6..d0a79a5f68e3ef9ffecc4a0b51af8c4a6e9f3351 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -90933,11 +90933,12 @@ value.
   <int value="2" label="Saved"/>
   <int value="3" label="RequestCoordinator canceled"/>
   <int value="4" label="Prerendering canceled"/>
-  <int value="5" label="Prerendering failed"/>
+  <int value="5" label="Prerendering failed (retryable)"/>
   <int value="6" label="Save failed"/>
   <int value="7" label="Foreground transition canceled"/>
   <int value="8" label="RequestCoordinator timed-out"/>
   <int value="9" label="Prerendering not started"/>
+  <int value="10" label="Prerendering failed (non-retryable)"/>
 </enum>
 
 <enum name="OfflinePagesClearAllStatus" type="int">