Document shutdown and suspend histograms for Chrome OS.

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 3b4f96a36ea8867a76e992ce0645844588653975..7e13fb926b2e64eaadaa631a4cab364194e843d1 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -14845,11 +14845,22 @@ other types of suffix sets.
 </histogram>
 
 <histogram name="Power.RetrySuspendCount">
+  <obsolete>
+    Deprecated Feb 2014 by Power.SuspendAttemptsBeforeCancel and
+    Power.SuspendAttemptsBeforeSuccess.
+  </obsolete>
   <summary>
     The number of times Chrome OS retried suspend due to previous failure.
   </summary>
 </histogram>
 
+<histogram name="Power.ShutdownReason" enum="ShutdownReason">
+  <summary>
+    The reason for the Chrome OS power manager shutting down or rebooting the
+    system.
+  </summary>
+</histogram>
+
 <histogram name="Power.SuspendAttempt" enum="SuspendAttempt">
   <summary>
     The number of suspend attempts on Chrome OS. Samples are reported before
@@ -14858,6 +14869,23 @@ other types of suffix sets.
   </summary>
 </histogram>
 
+<histogram name="Power.SuspendAttemptsBeforeCancel">
+  <summary>
+    The number of suspend attempts performed for a single suspend request (e.g.
+    triggered by the lid being closed) that was eventually canceled on Chrome
+    OS. This also includes requests that were canceled due to the system
+    eventually shutting down due to repeated suspend failures.
+  </summary>
+</histogram>
+
+<histogram name="Power.SuspendAttemptsBeforeSuccess">
+  <summary>
+    The number of suspend attempts performed for a single suspend request (e.g.
+    triggered by the lid being closed) that eventually succeeded on Chrome OS.
+    This includes the successful attempt.
+  </summary>
+</histogram>
+
 <histogram name="Power.SuspendResult" enum="SuspendResult">
   <summary>
     The results of suspend attempts on Chrome OS. Samples are reported after
@@ -30967,6 +30995,18 @@ other types of suffix sets.
   <int value="1" label="Failure"/>
 </enum>
 
+<enum name="ShutdownReason" type="int">
+  <summary>
+    The reason that the Chrome OS power manager shut down or rebooted the
+    system.
+  </summary>
+  <int value="0" label="User request"/>
+  <int value="1" label="State transition"/>
+  <int value="2" label="Low battery"/>
+  <int value="3" label="Suspend failures"/>
+  <int value="4" label="Dark resume"/>
+</enum>
+
 <enum name="SideloadUIEvents" type="int">
   <int value="0" label="Extension installed"/>
   <int value="1" label="Extension ignored"/>