Partial implementation of subscription restrictions.

third_party/WebKit/Source/modules/push_messaging/PushSubscriptionOptions.idl

Index: third_party/WebKit/Source/modules/push_messaging/PushSubscriptionOptions.idl
diff --git a/third_party/WebKit/Source/modules/push_messaging/PushSubscriptionOptions.idl b/third_party/WebKit/Source/modules/push_messaging/PushSubscriptionOptions.idl
index f0342421a0d10bc664fcd5358a493142fa8599b0..d86a314fbd5730993a92e3216e3c2eb6b660b491 100644
--- a/third_party/WebKit/Source/modules/push_messaging/PushSubscriptionOptions.idl
+++ b/third_party/WebKit/Source/modules/push_messaging/PushSubscriptionOptions.idl
@@ -6,4 +6,5 @@
 
 dictionary PushSubscriptionOptions {
     boolean userVisibleOnly = false;
+    ArrayBuffer applicationServerKey;

[Peter Beverloo, 2016/02/18 11:39:43]

As discussed, we'll want to hide this behind a feature flag annotation until the
feature can be shipped, e.g. [RuntimeEnabled=PushSubscriptionRestrictions],
whereas PushSubscriptionRestrictions can be enabled with the Enable Experimental
Web Platform Features command-line flag.

This gives us four possible values for the `applicationServerKey` property in
C++:

  (1) Feature flag disabled, developer does not provide `applicationServerKey`:
NULL.
  (2) Feature flag disabled, developer provides `applicationServerKey`: NULL.
  (3) Feature flag enabled, developer does not provide `applicationServerKey`:
NULL.
  (4) Feature flag enabled, developer provides `applicationServerKey`:
BufferSource value.

[Peter Beverloo, 2016/02/18 11:39:43]

Per the spec, this has to be of type BufferSource, which is an ArrayBuffer *or*
an ArrayBufferView.

We have the typedef in CommonDefinitions.idl already, so you should be able to
use it directly. You could extract the IDL value -> (Web)String conversion to a
helper method that abstracts this away from the main flow.

String toString(const ArrayBufferOrArrayBufferView& applicationServerKey) {
  if (applicationServerKey.isArrayBuffer()) { ... }
  else if (applicationServerKey.isArrayBufferView()) { ... }
  else { Oops!(); }
}

[harkness, 2016/02/22 15:40:43]

Should be good now?

 };