Stop showing notifications if they're ignored

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 294e24dd1d31f33ca0e03035d7e9d4a9786bc9bc..125dafa9e13450912a3513823ebce9e8b7e1e1bc 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -38872,6 +38872,36 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="NewTabPage.ContentSuggestions.Notifications.Actions"
+    enum="ContentSuggestionsNotificationsAction">
+  <owner>sfiera@chromium.org</owner>
+  <summary>
+    Android: The number of actions taken on displayed notifications, either
+    user-initiated (tapping to open or swiping to dismiss), or automatic (hiding
+    due to a change in circumstances).
+  </summary>
+</histogram>
+
+<histogram name="NewTabPage.ContentSuggestions.Notifications.Impressions"
+    enum="ContentSuggestionsNotificationsImpression">
+  <owner>sfiera@chromium.org</owner>
+  <summary>
+    Android: The number of notifications that were shown, keyed by category. One
+    bucket counts the server-provided ARTICLES category; the other counts
+    everything else.
+  </summary>
+</histogram>
+
+<histogram name="NewTabPage.ContentSuggestions.Notifications.OptOuts"
+    enum="ContentSuggestionsNotificationsOptOut">
+  <owner>sfiera@chromium.org</owner>
+  <summary>
+    Android: The number of times a user opted out, keyed by method: IMPLICIT
+    (user ignored enough notifications consecutively that we think they're not
+    interested), or EXPLICIT (via explicit setting).
+  </summary>
+</histogram>
+
 <histogram name="NewTabPage.ContentSuggestions.OpenDisposition"
     enum="WindowOpenDisposition">
   <owner>treib@chromium.org</owner>
@@ -80789,6 +80819,26 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <int value="6" label="Articles"/>
 </enum>
 
+<enum name="ContentSuggestionsNotificationsAction" type="int">
+  <int value="0" label="Tap"/>
+  <int value="1" label="Dismissal"/>
+  <int value="2" label="Hidden (Notification deadline passed)"/>
+  <int value="3" label="Hidden (Suggestion expired)"/>
+  <int value="4" label="Hidden (Chrome became frontmost)"/>
+  <int value="5" label="Hidden (Category disabled)"/>
+  <int value="6" label="Hidden (Content Suggestion Service shut down)"/>
+</enum>
+
+<enum name="ContentSuggestionsNotificationsImpression" type="int">
+  <int value="0" label="Article"/>
+  <int value="1" label="Non-Article"/>
+</enum>
+
+<enum name="ContentSuggestionsNotificationsOptOut" type="int">
+  <int value="0" label="Implicit"/>
+  <int value="1" label="Explicit"/>
+</enum>
+
 <enum name="ContentType" type="int">
   <int value="-1" label="Invalid setting"/>
   <int value="0" label="Cookies setting"/>