Adding MOJO_HANDLE_SIGNAL_PEER_CLOSED to be notified when a peer is closed.

mojo/public/java/system/src/org/chromium/mojo/system/Core.java

Index: mojo/public/java/system/src/org/chromium/mojo/system/Core.java
diff --git a/mojo/public/java/system/src/org/chromium/mojo/system/Core.java b/mojo/public/java/system/src/org/chromium/mojo/system/Core.java
index d6c8e7da8d47eaaa9e11ec1408ad3e68f6e380a1..dbcfc5dda2961e6d1504858294be75d1c39089e4 100644
--- a/mojo/public/java/system/src/org/chromium/mojo/system/Core.java
+++ b/mojo/public/java/system/src/org/chromium/mojo/system/Core.java
@@ -33,6 +33,7 @@ public interface Core {
         private static final int FLAG_NONE = 0;
         private static final int FLAG_READABLE = 1 << 0;
         private static final int FLAG_WRITABLE = 1 << 1;
+        private static final int FLAG_CLOSED = 1 << 2;
 
         /**
          * Immutable signals.
@@ -64,6 +65,16 @@ public interface Core {
         }
 
         /**
+         * Change the closed bit of this signal.
+         *
+         * @param closed the new value of the closed bit.
+         * @return this.
+         */
+        public HandleSignals setClosed(boolean closed) {
+            return setFlag(FLAG_CLOSED, closed);
+        }
+
+        /**
          * @return a signal with no bit set.
          */
         public static HandleSignals none() {