Implement cloud policy invalidations using the invalidation service framework.

tools/metrics/histograms/histograms.before.pretty-print.xml

Index: tools/metrics/histograms/histograms.before.pretty-print.xml
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.before.pretty-print.xml
similarity index 99%
copy from tools/metrics/histograms/histograms.xml
copy to tools/metrics/histograms/histograms.before.pretty-print.xml
index 897e120c7e2a02280e3cfc8d599edff57e305ea5..25cee638ef61f892439602a6ee846ae1c8be05c7 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.before.pretty-print.xml
@@ -2404,6 +2404,12 @@ other types of suffix sets.
   </summary>
 </histogram>
 
+<histogram name="Enterprise.PolicyInvalidations" enum="EnterprisePolicyInvalidations">
+  <summary>
+    Events for receiving different types of invalidations.
+  </summary>
+</histogram>
+
 <histogram name="Enterprise.PolicyLoadStatus" enum="EnterprisePolicyLoadStatus">
   <summary>
     Load status from the policy loaders which pull policy settings from the
@@ -2411,6 +2417,13 @@ other types of suffix sets.
   </summary>
 </histogram>
 
+<histogram name="Enterprise.PolicyRefresh" enum="EnterprisePolicyRefresh">
+  <summary>
+    Events measuring effectiveness of refreshing policy when invalidations
+    are received from a service.
+  </summary>
+</histogram>
+
 <histogram name="Event.CoalescedCount.Mouse">
   <summary>Number of Mouse events coalesced.</summary>
 </histogram>
@@ -15945,6 +15958,37 @@ other types of suffix sets.
   <int value="8" label="PARSE_ERROR">Parse error.</int>
 </enum>
 
+<enum name="EnterprisePolicyInvalidations" type="int">
+  <summary>
+    Status codes representing types of policy invalidations received.
+  </summary>
+  <int value="0" label="PAYLOAD">
+    The invalidation contains a payload.
+  </int>
+  <int value="1" label="NO_PAYLOAD">
+    The invalidation contains no payload.
+  </int>
+</enum>
+
+<enum name="EnterprisePolicyRefresh" type="int">
+  <summary>
+    Status codes representing whether a policy was invalidated when it was
+    refreshed and whether the refresh resulted in changed policy values.
+  </summary>
+  <int value="0" label="CHANGED">
+    Policy was not invalidated; policy was changed.
+  </int>
+  <int value="1" label="UNCHANGED">
+    Policy was not invalidated; policy was unchanged.
+  </int>
+  <int value="2" label="INVALIDATED_CHANGED">
+    Policy was invalidated; policy was changed.
+  </int>
+  <int value="3" label="INVALIDATED_UNCHANGED">
+    Policy was invalidated; policy was unchanged.
+  </int>
+</enum>
+
 <enum name="EnterprisePolicyType" type="int">
   <summary>
     Result of Policy operations as defined in