Add UMA histogram to show how many retries we had to do to execute a DeviceManagementRequestJob.

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 502f97d51c27ef34d5feda8a9f310394693dad50..ffc0cff73de9fb1bfce6aa7a7b3c5117ff0f689e 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -12733,6 +12733,17 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Enterprise.DMServerRequestSuccess"
+    enum="EnterpriseDMServerRequestSuccess">
+  <owner>hunyadym@chromium.org</owner>
+  <summary>
+    Number of retries the client did to execute a DeviceManagementServer
+    request. It's recorded after the request has been completed, either
+    successfully after 0 or more retries, with a failure (too many retries or
+    non-retriable error) or with a server error.
+  </summary>
+</histogram>
+
 <histogram name="Enterprise.DMToken" enum="EnterpriseDMTokenType">
   <owner>mnissler@chromium.org</owner>
   <summary>
@@ -78554,6 +78565,19 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <int value="902" label="SERVICE_POLICY_NOT_FOUND"/>
 </enum>
 
+<enum name="EnterpriseDMServerRequestSuccess" type="int">
+  <summary>
+    Number of DeviceManagementServer request retries as defined in
+    components/policy/core/common/cloud/device_management_service.cc.
+  </summary>
+  <int value="0" label="No retries"/>
+  <int value="1" label="1 retry"/>
+  <int value="2" label="2 retries"/>
+  <int value="3" label="3 retries"/>
+  <int value="10" label="Request failed"/>
+  <int value="11" label="Server returned error"/>
+</enum>
+
 <enum name="EnterpriseDMTokenType" type="int">
   <summary>
     Result of DMToken operations as defined in