Adding a router class to handle messages that expect responses.

mojo/bindings/java/src/org/chromium/mojo/bindings/Struct.java

Index: mojo/bindings/java/src/org/chromium/mojo/bindings/Struct.java
diff --git a/mojo/bindings/java/src/org/chromium/mojo/bindings/Struct.java b/mojo/bindings/java/src/org/chromium/mojo/bindings/Struct.java
index f7c16a2decb0fa75c54e0684ed020a1b6bfa9163..dc1742a3491a87a1b6385abc2dd65084fa1ede3a 100644
--- a/mojo/bindings/java/src/org/chromium/mojo/bindings/Struct.java
+++ b/mojo/bindings/java/src/org/chromium/mojo/bindings/Struct.java
@@ -42,6 +42,35 @@ public abstract class Struct {
             this.size = size;
             this.numFields = numFields;
         }
+
+        /**
+         * @see Object#hashCode()
+         */
+        @Override
+        public int hashCode() {
+            final int prime = 31;
+            int result = 1;
+            result = prime * result + numFields;
+            result = prime * result + size;
+            return result;
+        }
+
+        /**
+         * @see Object#equals(Object)
+         */
+        @Override
+        public boolean equals(Object object) {
+            if (object == this)
+                return true;
+            if (object == null)
+                return false;
+            if (getClass() != object.getClass())
+                return false;
+
+            DataHeader other = (DataHeader) object;
+            return (numFields == other.numFields &&
+                    size == other.size);
+        }
     }
 
     /**
@@ -73,4 +102,18 @@ public abstract class Struct {
         return encoder.getMessage();
     }
 
+    /**
+     * Returns the serialization of the struct prepended with the given header.
+     *
+     * @param header the header to prepend to the returned message.
+     * @param core the |Core| implementation used to generate handles. Only used if the |Struct|
+     *            being encoded contains interfaces, can be |null| otherwise.
+     */
+    public MessageWithHeader serializeWithHeader(Core core, MessageHeader header) {
+        Encoder encoder = new Encoder(core, mEncodedBaseSize + header.getSize());
+        header.encode(encoder);
+        encode(encoder);
+        return new MessageWithHeader(encoder.getMessage(), header);
+    }
+
 }