Push API: Store push registration IDs for GetRegistration etc

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 6ac9d962c1ea4e70233a469b40f4440a2c136541..21e7f4561504eba71d58d428c2d4d10b3e6b0ad2 100644
--- a/content/public/common/push_messaging_status.h
+++ b/content/public/common/push_messaging_status.h
@@ -31,13 +31,16 @@ enum PushRegistrationStatus {
   // Registration failed because no sender id was provided by the page.
   PUSH_REGISTRATION_STATUS_NO_SENDER_ID = 6,
 
+  // Registration suceeded, but we failed to persist it.

[Avi (use Gerrit), 2014/12/05 20:50:22]

s/suceeded/succeeded/

[johnme, 2014/12/05 21:56:33]

Done.

+  PUSH_REGISTRATION_STATUS_STORAGE_ERROR = 7,

[Avi (use Gerrit), 2014/12/05 20:50:22]

I'm curious: if a registration succeeded but wasn't persisted, is it a useful
registration? What is the caller supposed to do upon getting this reply?

[johnme, 2014/12/05 21:56:33]

As well as it being one of the outcomes we log to UMA (to detect failure modes),
the caller will bubble up the error to JavaScript. The spec says[1] to fire a
DOMException whose `name` is "AbortError" for an errors that occur during
registration. But we'll set the `message`[2] of the DOMException to the string
produced by content::PushRegistrationStatusToString.

Thus a web developer who encounters this error
a) might be better able to guess at the cause,
b) can include it on stackoverflow and bug reports etc,
c) they or we will then be able to grep through the chromium source to find the
relevant code.

[1]:
https://w3c.github.io/push-api/#widl-PushRegistrationManager-register-Promise...

[2]: http://heycam.github.io/webidl/#dfn-exception-message

+
   // 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_REGISTRATION_STATUS_LAST below.
 
   // Used for IPC message range checks.
-  PUSH_REGISTRATION_STATUS_LAST = PUSH_REGISTRATION_STATUS_NO_SENDER_ID
+  PUSH_REGISTRATION_STATUS_LAST = PUSH_REGISTRATION_STATUS_STORAGE_ERROR
 };
 
 // Push message delivery success / error codes for internal use.