Make Service Worker DB UserData methods accept multiple keys at once

content/browser/service_worker/service_worker_context_wrapper.h

Index: content/browser/service_worker/service_worker_context_wrapper.h
diff --git a/content/browser/service_worker/service_worker_context_wrapper.h b/content/browser/service_worker/service_worker_context_wrapper.h
index fec09d0240a24760c54236b5c53e68fadaa8f4fb..b5f5fed2418fb8a0d4d63ed74a53adf19706e6f4 100644
--- a/content/browser/service_worker/service_worker_context_wrapper.h
+++ b/content/browser/service_worker/service_worker_context_wrapper.h
@@ -154,15 +154,15 @@ class CONTENT_EXPORT ServiceWorkerContextWrapper
   // All these methods must be called from the IO thread.
   void GetAllRegistrations(const GetRegistrationsInfosCallback& callback);
   void GetRegistrationUserData(int64_t registration_id,
-                               const std::string& key,
+                               const std::vector<std::string>& keys,

[Michael van Ouwerkerk, 2016/05/04 09:08:52]

nit: why not std::set<std::string>?

[johnme, 2016/05/05 10:54:04]

Because the order of the results is based on the order of these keys (and having
the result order depend on the lexicographic order of the keys would be hella
confusing).

It could be a std::set for Clear, but consistency seemed nice.

                                const GetUserDataCallback& callback);
-  void StoreRegistrationUserData(int64_t registration_id,
-                                 const GURL& origin,
-                                 const std::string& key,
-                                 const std::string& data,
-                                 const StatusCallback& callback);
+  void StoreRegistrationUserData(
+      int64_t registration_id,
+      const GURL& origin,
+      const std::vector<std::pair<std::string, std::string>>& key_value_pairs,

[Michael van Ouwerkerk, 2016/05/04 09:08:52]

nit: why not std::map<std::string, std::string>?

[johnme, 2016/05/05 10:54:04]

I considered this, as both std::map and std::unordered_map would have the same
initializer_lists, but they perform slightly worse (especially since this gets
copied during the thread-hop, which would cause a 2nd n log n, or a re-hashing
of all the keys), and it seems slightly cleaner for the order of writes to be as
specified, rather than alphabetical by key or arbitrary (for example this makes
the tests deterministic). But I could go either way on this.

+      const StatusCallback& callback);
   void ClearRegistrationUserData(int64_t registration_id,
-                                 const std::string& key,
+                                 const std::vector<std::string>& keys,
                                  const StatusCallback& callback);
   void GetUserDataForAllRegistrations(
       const std::string& key,