Add UMA for recording embargo reasons and autoblocker interactions.

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 f6a3aa9a7c846f867e1938c5f5fa3dfc50f86021..f78080b4dda612eae9beb5d5561a14854441db72 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -46045,6 +46045,20 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Permissions.AutoBlocker.EmbargoStatus"
+    enum="PermissionEmbargoStatus">
+  <owner>dominickn@chromium.org</owner>
+  <owner>kcarattini@chromium.org</owner>
+  <summary>
+    Tracks the reason that an (origin, permission) pair has been placed under
+    embargo (blocked from making requests for that permission for a period of
+    time). This is triggered when a permission is placed under embargo for
+    blacklisting (once Safe Browsing has returned a result), when a permission
+    prompt has been shown and it is placed under embargo for repeated
+    dismissals, or when a permission prompt is shown and not embargoed.
+  </summary>
+</histogram>
+
 <histogram name="Permissions.AutoBlocker.SafeBrowsingResponse"
     enum="SafeBrowsingResponse">
   <owner>dominickn@chromium.org</owner>
@@ -102339,6 +102353,12 @@ value.
   <int value="4" label="REVOKED"/>
 </enum>
 
+<enum name="PermissionEmbargoStatus" type="int">
+  <int value="0" label="NOT_EMBARGOED"/>
+  <int value="1" label="BLACKLISTED"/>
+  <int value="2" label="REPEATED_DISMISSALS"/>
+</enum>
+
 <enum name="PermissionRequestType" type="int">
   <int value="0" label="PERMISSION_BUBBLE_UNKNOWN"/>
   <int value="1" label="PERMISSION_BUBBLE_MULTIPLE"/>