Introduce moderate binding

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 bd56cb27746bc01175dd333d21c9e0c028399842..e4edc642c385e4729c2f5c59dccd6728aed77fcf 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -268,6 +268,14 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Android.ModerateBindingCount">

[Alexei Svitkine (slow), 2015/06/17 16:57:22]

Nit: add units=

[Jaekyun Seok (inactive), 2015/06/17 22:31:51]

Done.

+  <owner>jaekyun@chromium.org</owner>
+  <summary>
+    The number of moderate bindings which were kept while Chrome process is in
+    the foreground.

[Alexei Svitkine (slow), 2015/06/17 16:57:22]

Mention when this is logged.

[Jaekyun Seok (inactive), 2015/06/17 22:31:51]

Done.

+  </summary>
+</histogram>
+
 <histogram name="Android.SeccompStatus.Prctl" enum="AndroidSeccompStatus">
   <owner>rsesek@chromium.org</owner>
   <summary>
@@ -44046,6 +44054,14 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Tab.TotalTabCountBeforeLeavingApp">

[Alexei Svitkine (slow), 2015/06/17 16:57:22]

Nit: Add units=

[Jaekyun Seok (inactive), 2015/06/17 22:31:51]

Done.

+  <owner>jaekyun@chromium.org</owner>
+  <summary>
+    The total count of tabs which were kept while Chrome process is in the
+    foreground.

[Alexei Svitkine (slow), 2015/06/17 16:57:22]

Mention when this is logged.

[Jaekyun Seok (inactive), 2015/06/17 22:31:51]

Done.

+  </summary>
+</histogram>
+
 <histogram name="Tabs.CountAtResume" units="tabs">
   <owner>lliabraa@chromium.org</owner>
   <summary>