Add metrics to keep track of the tab activate/deactivate cycle

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 785ef1d286628219bbea4a07beb00865a717983c..d3b4c7383633c17f624457f81fd5d2ab7136d698 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -61621,6 +61621,30 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Tab.Deactivation.Bookmarked" enum="Boolean">
+  <owner>pmonette@chromium.org</owner>
+  <summary>
+    The number of times a tab was deactivated, excluding closing tabs. This

[rkaplow, 2016/09/21 14:16:55]

This isn't the "number of times" - since that implies you are storing a count
here. I would treat the description as a single instance of data being stored in
the histogram. I'd modify all the descriptions in this way

[Patrick Monette, 2016/09/21 21:03:18]

Done.

+    histogram also records if the tab's URL was bookmarked.
+  </summary>
+</histogram>
+
+<histogram name="Tab.Deactivation.HadFormInteraction" enum="Boolean">
+  <owner>pmonette@chromium.org</owner>
+  <summary>
+    The number of times a tab was deactivated, excluding closing tabs. This
+    histogram also records if the tab had any form interaction.
+  </summary>
+</histogram>
+
+<histogram name="Tab.Deactivation.Pinned" enum="Boolean">
+  <owner>pmonette@chromium.org</owner>
+  <summary>
+    The number of times a tab was deactivated, excluding closing tabs. This
+    histogram also records if the tab was pinned to tab strip or not.
+  </summary>
+</histogram>
+
 <histogram name="Tab.Discarding" enum="TabDiscardingEvents">
   <obsolete>
     Deprecated 10/2015, not needed anymore.
@@ -61722,6 +61746,30 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Tab.Reactivation.Bookmarked" enum="Boolean">
+  <owner>pmonette@chromium.org</owner>
+  <summary>
+    The number of times a tab was activated following a deactivation. This
+    histogram also records if the tab's URL was bookmarked.
+  </summary>
+</histogram>
+
+<histogram name="Tab.Reactivation.HadFormInteraction" enum="Boolean">
+  <owner>pmonette@chromium.org</owner>
+  <summary>
+    The number of times a tab was activated following a deactivation. This
+    histogram also records if the tab had any form interaction.
+  </summary>
+</histogram>
+
+<histogram name="Tab.Reactivation.Pinned" enum="Boolean">
+  <owner>pmonette@chromium.org</owner>
+  <summary>
+    The number of times a tab was activated following a deactivation. This
+    histogram also records if the tab was pinned to the tab strip.
+  </summary>
+</histogram>
+
 <histogram name="Tab.RendererCrashStatus" enum="TabRendererCrashStatus">
   <owner>jaekyun@chromium.org</owner>
   <summary>