extensions: Relocate pref name constants.

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 70c7011d7db68afea76946a6d449b2aca488d3fc..4b30b7b68265f135454f0e5dc20d5ca79e1ae4d0 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -30823,14 +30823,14 @@ other types of suffix sets.
   <int value="2" label="prefs::kHomePage"/>
   <int value="3" label="prefs::kRestoreOnStartup"/>
   <int value="4" label="prefs::kURLsToRestoreOnStartup"/>
-  <int value="5" label="prefs::kExtensionsPref"/>
+  <int value="5" label="extensions::pref_names::kExtensions"/>
   <int value="6" label="prefs::kGoogleServicesLastUsername"/>
   <int value="7" label="prefs::kSearchProviderOverrides"/>
   <int value="8" label="prefs::kDefaultSearchProviderSearchURL"/>
   <int value="9" label="prefs::kDefaultSearchProviderKeyword"/>
   <int value="10" label="prefs::kDefaultSearchProviderName"/>
   <int value="11" label="prefs::kPinnedTabs"/>
-  <int value="12" label="prefs::kExtensionKnownDisabled"/>
+  <int value="12" label="extensions::pref_names::kKnownDisabled"/>
   <int value="13" label="prefs::kProfileResetPromptMemento"/>
 </enum>