[NTP::SectionOrder] Add a flag to choose category ranker.

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 817f4bc81b23e3553e473e72f7a307de0f4207ff..bb3e388d49b2d06eae2f7da1816eb2830eca9fea 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -93792,6 +93792,7 @@ value.
   <int value="-345838366" label="enable-hosted-apps-in-windows"/>
   <int value="-345324571" label="enable-quirks-client"/>
   <int value="-344343842" label="disable-experimental-app-list"/>
+  <int value="-342292226" label="ntp-category-ranker"/>
   <int value="-340622848" label="disable-javascript-harmony-shipping"/>
   <int value="-340255045" label="allow-nacl-socket-api"/>
   <int value="-329727402" label="disable-files-quick-view"/>
@@ -94075,6 +94076,7 @@ value.
   <int value="1050048304" label="enable-font-cache-scaling"/>
   <int value="1050321458" label="new-profile-management"/>
   <int value="1054910800" label="enable-timezone-tracking-option"/>
+  <int value="1058489007" label="NTPCategoryRanker:disabled"/>
   <int value="1060319397" label="enable-data-reduction-proxy-carrier-test"/>
   <int value="1062357243" label="remember-cert-error-decisions"/>
   <int value="1064288458" label="OfflineRecentPages:enabled"/>
@@ -94146,6 +94148,7 @@ value.
   <int value="1318073661" label="MaterialDesignExtensions:enabled"/>
   <int value="1319725131" label="enable-distance-field-text"/>
   <int value="1320201920" label="enable-touchpad-three-finger-click"/>
+  <int value="1324449665" label="NTPCategoryRanker:enabled"/>
   <int value="1344833841" label="ImeThread:enabled"/>
   <int value="1351830811" label="do-not-ignore-autocomplete-off"/>
   <int value="1352447982" label="enable-lcd-text"/>