NTP: simplify mojo connection setup

chrome/common/instant.mojom

Index: chrome/common/instant.mojom
diff --git a/chrome/common/instant.mojom b/chrome/common/instant.mojom
index 3935339e2d3330fa915abbdee2e9be117069f655..20c69d3b892dd205453b23c41508754b9eb9ccd7 100644
--- a/chrome/common/instant.mojom
+++ b/chrome/common/instant.mojom
@@ -17,6 +17,17 @@ enum OmniboxFocusState;
 [Native]
 enum NTPTileSource;
 
+// Interface used to connect to the new tab page (NTP) interface. This is a
+// separate interface such that a reverse connection (|search_box| below) can be
+// passed when connecting.

[dcheng, 2017/02/08 09:01:39]

Thanks for adding these comments. Mind describing the purpose of the
Instant/SearchBox interfaces as well? =)

[tibell, 2017/02/09 03:35:28]

I've added some more comments to express my current understanding.

+interface NTPConnector {

[Marc Treib, 2017/02/08 10:00:36]

Per my other comment: I don't think "NTP" is the right name here.
"EmbeddedSearchConnector"?

[tibell, 2017/02/09 03:35:28]

Done.

+  // Connect to the interface. |instant| is the connection which the client will
+  // use to query the NTP interface. |search_box| is the connection used by the
+  // NTP interface implementation to push browser state updates to the client.
+  Connect(associated Instant& instant, associated SearchBox search_box);
+};
+
+// TODO(tibell): Rename this to NTP.
 interface Instant {
   // Tells InstantExtended whether the embedded search API is supported.
   // See http://dev.chromium.org/embeddedsearch