Limit number of service instances passed to onServiceList listeners.

chrome/common/extensions/api/mdns.idl

Index: chrome/common/extensions/api/mdns.idl
diff --git a/chrome/common/extensions/api/mdns.idl b/chrome/common/extensions/api/mdns.idl
index 434d4b8187ff8912241fdae3b3d81a152dfbb31a..88d73dd36a37761a75c38cbbba7d65229dea33d5 100644
--- a/chrome/common/extensions/api/mdns.idl
+++ b/chrome/common/extensions/api/mdns.idl
@@ -23,6 +23,22 @@ namespace mdns {
     DOMString[] serviceData;
   };
 
+  callback GetMaxServiceInstancesPerEvent = void (long n);
+
+  /*
+  enum Constants {
+    MaxServiceInstancesPerEvent = 64
+    //static long getMaxServiceInstancesPerEvent ();
+  }
+  */
+  interface Functions {
+    // The maximum number of service instances that will be included in

[not at google - send to devlin, 2015/04/01 20:25:58]

Sorry for the delay with this review, but I'm adding support for constants here:
https://codereview.chromium.org/1051563002 after which you'd be able to write
this properly (if unfortunately syntactically) as:

interface Properties {
  // The maximum number...
  [value=64] static long maxServiceInstancesPerEvent();
}

pretty similar to what you have, just it'd be a property rather than a getter
(and therefore accessible synchronously).

Also, the typical style for constants has been MAX_SERVICE_INSTANCES_PER_EVENT.

Up to you whether you want to wait for that CL to go in I suppose, but consider
it.

[Red Daly, 2015/04/01 22:52:05]

That works for me except I'm trying to commit before Friday's branch.  If the
other CL lands before end of tomorrow, I can change this API accordingly.

[Red Daly, 2015/04/02 22:25:21]

Thanks for that - updated.  Please take another look.

Note that I didn't update to use the MAX_SERVICE_INSTANCES_PER_EVENT style
because I interpret your comment to mean the CAPS_STYLE is for C++ code.  I
think camelCase is the convention in JavaScript APIs.

[not at google - send to devlin, 2015/04/02 22:36:22]

AFAIK Caps is the style for web APIs, e.g. see the constants in KeyboardEvent.

[Red Daly, 2015/04/03 17:58:55]

Done.

+    // onServiceList events.  If more instances are available, they may be
+    // truncated from the onServiceList event.
+    static void getMaxServiceInstancesPerEvent (
+        GetMaxServiceInstancesPerEvent callback);
+  };
+
   interface Events {
     // Event fired to inform clients of the current complete set of known
     // available services. Clients should only need to store the list from the