Push API: Refactor and fix unsubscribe API

content/public/common/push_messaging_status.h

Index: content/public/common/push_messaging_status.h
diff --git a/content/public/common/push_messaging_status.h b/content/public/common/push_messaging_status.h
index 9dd87ebcc54f3519296897a111ec1a20a81ed6bb..45fc412cca35f0f97008b1ccdbdc48174fa979af 100644
--- a/content/public/common/push_messaging_status.h
+++ b/content/public/common/push_messaging_status.h
@@ -65,6 +65,32 @@ enum PushRegistrationStatus {
       PUSH_REGISTRATION_STATUS_MANIFEST_EMPTY_OR_MISSING
 };
 
+// Push unregistration reason for reporting in UMA.
+enum PushUnregistrationReason {
+  // Unregistering because the website called the unsubscribe API.
+  PUSH_UNREGISTRATION_REASON_JAVASCRIPT_API = 0,
+
+  // Unregistering because the user manually revoked permission.
+  PUSH_UNREGISTRATION_REASON_PERMISSION_REVOKED = 1,
+
+  // Automatic - incoming message's app id was unknown.
+  PUSH_UNREGISTRATION_REASON_DELIVERY_UNKNOWN_APP_ID = 2,
+
+  // Automatic - incoming message's origin no longer has permission.
+  PUSH_UNREGISTRATION_REASON_DELIVERY_PERMISSION_DENIED = 3,
+
+  // Automatic - incoming message's service worker was not found.
+  PUSH_UNREGISTRATION_REASON_DELIVERY_NO_SERVICE_WORKER = 4,
+
+  // NOTE: Do not renumber these as that would confuse interpretation of
+  // previously logged data. When making changes, also update the enum list
+  // in tools/metrics/histograms/histograms.xml to keep it in sync, and
+  // update PUSH_UNREGISTRATION_REASON_LAST below.
+
+  PUSH_UNREGISTRATION_REASON_LAST =
+      PUSH_UNREGISTRATION_REASON_DELIVERY_NO_SERVICE_WORKER
+};
+
 // Push unregistration success/error codes for internal use & reporting in UMA.
 enum PushUnregistrationStatus {
   // The unregistration was successful.