Clean up descriptions and add metrics for the Data Saver UI

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 d476b29069e83525241378e66c58b9d231e3693f..6a31b5cb558c50e792b91a7194db4e589a903221 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -10481,20 +10481,8 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <owner>megjablon@chromium.org</owner>
   <summary>
     Samples of user interactions with the Data Reduction Proxy promos, First Run
-    Experience, and settings menu. All samples are mutually exclusive. These
-    samples include:
-
-    The user interactions with the second run promo. On Android, there are three
-    actions that dismiss this promo (enable, dismiss, and learn more) and on iOS
-    there is a toggle to enable the proxy. This is sampled when the promo leaves
-    view. If the user clicks the link to the settings menu, the state of the
-    ON/OFF switch in the menu is sampled when the view is exited.
-
-    Any other user interaction with the the ON/OFF switch in the settings menu
-    for reducing data usage. Only the setting changes between entering the
-    reducing data usage setting menu and leaving the menu will be sampled
-    regardless of how many times they toggle the ON/OFF switch. Other samples
-    that report ON/OFF settings menu changes are not also reported here.
+    Experience, main menu footer, and settings menu. All samples are mutually
+    exclusive. These samples include:
 
     The user interactions with the First Run Experience. On Android when the
     user sees the FRE card, the Data Reduction Proxy defaults to ON. The user
@@ -10502,13 +10490,32 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
     sampled when the First Run Experience is completed and only reported if the
     Data Reduction Proxy card was shown.
 
+    The user interactions with the second run promo. On Android, there are two
+    actions that dismiss this promo (enable or dismiss). This is sampled when
+    the promo leaves view.
+
     The user interactions with the Infobar promo. On Android, there are two
     actions that dismiss the promo (enable, dismiss). This is sampled when the
     promo leaves view.
 
     The user interactions with the Snackbar promo. The user can either ignore
-    the promo or click the action to the Settings menu. From the settings menu,
+    the promo or click the action to the settings menu. From the settings menu,
     the user may enable or disable the proxy.
+
+    The user interactions with the main menu footer. The user can click the
+    footer to enter the settings menu. From the settings menu, the user may
+    enable or disable the proxy.
+
+    Any other user interaction with the ON/OFF switch in the settings menu for
+    reducing data usage. Only the setting changes between entering the reducing
+    data usage setting menu and leaving the menu will be sampled regardless of
+    how many times they toggle the ON/OFF switch. Other samples that report
+    ON/OFF settings menu changes are not also reported here.
+
+    The views of and user interactions with the site breakdown in the settings
+    menu. The site breakdown can be sorted by data saved descending or data used
+    descending, and expanded to view more sites. The Data Reduction statistics
+    can also be reset.
   </summary>
 </histogram>
 
@@ -89305,18 +89312,24 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
       label="Snackbar promo link clicked, and the proxy was disabled"/>
   <int value="15" label="Snackbar promo dismissed (no action taken)"/>
   <int value="16"
-      label="Arrived at settings menu by main menu item: entered off, exited
-             off"/>
+      label="Arrived at settings menu by main menu footer: entered off,
+             exited off"/>
   <int value="17"
-      label="Arrived at settings menu by main menu item: entered off, exited
-             on"/>
+      label="Arrived at settings menu by main menu footer: entered off,
+             exited on"/>
   <int value="18"
-      label="Arrived at settings menu by main menu item: entered on, exited
+      label="Arrived at settings menu by main menu footer: entered on, exited
              off"/>
   <int value="19"
-      label="Arrived at settings menu by main menu item: entered on, exited
+      label="Arrived at settings menu by main menu footer: entered on, exited
              on"/>
   <int value="20" label="Data usage stats reset via the settings menu"/>
+  <int value="21" label="Main menu footer displayed on"/>
+  <int value="22" label="Main menu footer displayed off"/>
+  <int value="23" label="Site breakdown displayed on the settings menu"/>
+  <int value="24" label="Site breakdown sorted by data saved"/>
+  <int value="25" label="Site breakdown sorted by data used"/>
+  <int value="26" label="Site breakdown expanded to see more sites"/>
 </enum>
 
 <enum name="DataUrlMimeType" type="int">