Unify UUID/GUID generation code across base and blink

chrome/browser/push_messaging/push_messaging_app_identifier.cc

Index: chrome/browser/push_messaging/push_messaging_app_identifier.cc
diff --git a/chrome/browser/push_messaging/push_messaging_app_identifier.cc b/chrome/browser/push_messaging/push_messaging_app_identifier.cc
index d4f7e7063188aadd5c5ab6cedf9ebfeba8b1cc0b..ece6b7a1d9817b67a8f932227bfd072b5b1e7633 100644
--- a/chrome/browser/push_messaging/push_messaging_app_identifier.cc
+++ b/chrome/browser/push_messaging/push_messaging_app_identifier.cc
@@ -66,7 +66,9 @@ void PushMessagingAppIdentifier::RegisterProfilePrefs(
 PushMessagingAppIdentifier PushMessagingAppIdentifier::Generate(
     const GURL& origin,
     int64_t service_worker_registration_id) {
-  std::string guid = base::GenerateGUID();
+  // Always use the uppercased GUID to to make the case mangling handling

[johnme, 2016/04/22 12:02:27]

Nit: Keeping these uppercase makes sense, but the primary reason is just for
consistency, so we don't end up with a mix of cases on the server. The following
comment might be clearer:

  // Use uppercase GUID for consistency with GUIDs Push has already sent to GCM.
  // Also allows detecting case mangling; see code commented "crbug.com/461867".

[kinuko, 2016/04/25 14:24:37]

Done.

+  // easier (see the code commented with crbug.com/461867).
+  std::string guid = base::ToUpperASCII(base::GenerateGUID());
   CHECK(!guid.empty());
   std::string app_id =
       kPushMessagingAppIdentifierPrefix + origin.spec() + kSeparator + guid;