Push API: Return cached registration if available.

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 ef5bf4fbda8a447f077d1e2c300619379a28607f..eaf71859f2cb973f885581639105a88c13f37874 100644
--- a/content/public/common/push_messaging_status.h
+++ b/content/public/common/push_messaging_status.h
@@ -12,27 +12,30 @@ enum PushRegistrationStatus {
   // Registration was successful.
   PUSH_REGISTRATION_STATUS_SUCCESS = 0,
 
+  // A successful registration was already cached in Service Worker storage.
+  PUSH_REGISTRATION_STATUS_SUCCESS_FROM_CACHE = 1,
+
   // Registration failed because there is no Service Worker.
-  PUSH_REGISTRATION_STATUS_NO_SERVICE_WORKER = 1,
+  PUSH_REGISTRATION_STATUS_NO_SERVICE_WORKER = 2,
 
   // Registration failed because the push service is not available.
-  PUSH_REGISTRATION_STATUS_SERVICE_NOT_AVAILABLE = 2,
+  PUSH_REGISTRATION_STATUS_SERVICE_NOT_AVAILABLE = 3,
 
   // Registration failed because the maximum number of registratons has been
   // reached.
-  PUSH_REGISTRATION_STATUS_LIMIT_REACHED = 3,
+  PUSH_REGISTRATION_STATUS_LIMIT_REACHED = 4,
 
   // Registration failed because permission was denied.
-  PUSH_REGISTRATION_STATUS_PERMISSION_DENIED = 4,
+  PUSH_REGISTRATION_STATUS_PERMISSION_DENIED = 5,
 
   // Registration failed in the push service implemented by the embedder.
-  PUSH_REGISTRATION_STATUS_SERVICE_ERROR = 5,
+  PUSH_REGISTRATION_STATUS_SERVICE_ERROR = 6,
 
   // Registration failed because no sender id was provided by the page.
-  PUSH_REGISTRATION_STATUS_NO_SENDER_ID = 6,
+  PUSH_REGISTRATION_STATUS_NO_SENDER_ID = 7,
 
   // Registration succeeded, but we failed to persist it.
-  PUSH_REGISTRATION_STATUS_STORAGE_ERROR = 7,
+  PUSH_REGISTRATION_STATUS_STORAGE_ERROR = 8,
 
   // NOTE: Do not renumber these as that would confuse interpretation of
   // previously logged data. When making changes, also update the enum list