Add feature to control showing suggestion summaries.

tools/metrics/histograms/enums.xml

Index: tools/metrics/histograms/enums.xml
diff --git a/tools/metrics/histograms/enums.xml b/tools/metrics/histograms/enums.xml
index 816d6b7841b4c0e36de95a1653809b41b6af9c8e..7706ee13dd88bf9a048d2e463381ce450826ceaa 100644
--- a/tools/metrics/histograms/enums.xml
+++ b/tools/metrics/histograms/enums.xml
@@ -21600,6 +21600,7 @@ from previous Chrome versions.
   <int value="-99781021" label="disable-roboto-font-ui"/>
   <int value="-89690053" label="MaterialDesignUserManager:enabled"/>
   <int value="-88822940" label="ssl-version-min"/>
+  <int value="-88273414" label="ContentSuggestionsShowSummary:enabled"/>
   <int value="-86788587" label="allow-autofill-sync-credential"/>
   <int value="-80353187" label="disable-display-color-calibration"/>
   <int value="-78035185" label="custom_summary"/>
@@ -21850,6 +21851,7 @@ from previous Chrome versions.
   <int value="886907524" label="autoplay-policy"/>
   <int value="887011602" label="enable-spelling-auto-correct"/>
   <int value="892899792" label="MaterialDesignIncognitoNTP:disabled"/>
+  <int value="900614020" label="ContentSuggestionsShowSummary:disabled"/>
   <int value="902608487" label="AutofillUpstreamRequestCvcIfMissing:enabled"/>
   <int value="903267263" label="disable-offline-pages"/>
   <int value="908523940" label="PassiveEventListenersDueToFling:disabled"/>