[chrome.displaySource] Session notification improvements

extensions/common/api/display_source.idl

Index: extensions/common/api/display_source.idl
diff --git a/extensions/common/api/display_source.idl b/extensions/common/api/display_source.idl
index f65a82a287aef889d518303f9925a4ac1fcb29f9..83cfa0dec50a4d0ade43f36195101a7c48689e5f 100644
--- a/extensions/common/api/display_source.idl
+++ b/extensions/common/api/display_source.idl
@@ -144,9 +144,6 @@ namespace displaySource {
     // or properties)
     // |sinks| the list of all currently available sinks
     static void onSinksUpdated(SinkInfo[] sinks);
-    // Event fired when the Display session is started.
-    // |sinkId| Id of the peer sink
-    [nocompile] static void onSessionStarted(long sinkId);
     // Event fired when the Display session is terminated.
     // |sinkId| Id of the peer sink
     [nocompile] static void onSessionTerminated(long sinkId);