Bring the feedback button to the Mac sad tab

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 cc984f5a562f0e0ff4cc303c8d5d24f5f7a55865..29d2bbe242e7aaa9170953a0e11040e0f429c9ba 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -60631,6 +60631,23 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Tabs.SadTab.StyleFeedback" enum="SadTabEvent">
+  <owner>sdy@chromium.org</owner>
+  <summary>
+    Counts of events from the style of sad tab which has a feedback button as
+    its primary action. Currently, events include being displayed (actually
+    visible in a window), and the actions a user can take on the page.
+  </summary>
+</histogram>
+
+<histogram name="Tabs.SadTab.StyleReload" enum="SadTabEvent">
+  <owner>sdy@chromium.org</owner>
+  <summary>
+    Counts of events from the style of sad tab which has a reload button as its
+    primary action. Compare to Tabs.SadTab.StyleFeedback.
+  </summary>
+</histogram>
+
 <histogram name="Tabs.ScrubDistance" units="tabs">
   <owner>Please list the metric's owners. Add more owner tags as needed.</owner>
   <summary>
@@ -91123,6 +91140,12 @@ To add a new entry, add it with any value and run test to compute valid value.
   <int value="1" label="Tabbed Mode"/>
 </enum>
 
+<enum name="SadTabEvent" type="int">
+  <int value="0" label="Displayed"/>
+  <int value="1" label="Button clicked"/>
+  <int value="2" label="Learn more clicked"/>
+</enum>
+
 <enum name="SadTabKind" type="int">
   <int value="0" label="Crash (Aw, Snap!)"/>
   <int value="1" label="Kill (He's dead, Jim!)"/>