Add serialization/deserialization of structs for mojo java bindings.

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 54bf3558d5323b78fc5aa94a888c5c141d39105f..f7c16a2decb0fa75c54e0684ed020a1b6bfa9163 100644
--- a/mojo/bindings/java/src/org/chromium/mojo/bindings/Struct.java
+++ b/mojo/bindings/java/src/org/chromium/mojo/bindings/Struct.java
@@ -4,9 +4,73 @@
 
 package org.chromium.mojo.bindings;
 
+import org.chromium.mojo.system.Core;
+
 /**
  * Base class for all mojo structs.
  */
 public abstract class Struct {
 
+    /**
+     * The header for a mojo complex element.
+     */
+    public static final class DataHeader {
+
+        /**
+         * The size of a serialized header, in bytes.
+         */
+        public static final int HEADER_SIZE = 8;
+
+        /**
+         * The offset of the size field.
+         */
+        public static final int SIZE_OFFSET = 0;
+
+        /**
+         * The offset of the number of fields field.
+         */
+        public static final int NUM_FIELDS_OFFSET = 4;
+
+        public final int size;
+        public final int numFields;
+
+        /**
+         * Constructor.
+         */
+        public DataHeader(int size, int numFields) {
+            super();
+            this.size = size;
+            this.numFields = numFields;
+        }
+    }
+
+    /**
+     * The base size of the struct.
+     */
+    protected final int mEncodedBaseSize;
+
+    /**
+     * Constructor.
+     */
+    protected Struct(int encodedBaseSize) {
+        this.mEncodedBaseSize = encodedBaseSize;
+    }
+
+    /**
+     * Use the given encoder to serialized this struct.
+     */
+    protected abstract void encode(Encoder encoder);
+
+    /**
+     * Returns the serialization of the struct. This method can close Handles.
+     *
+     * @param core the |Core| implementation used to generate handles. Only used if the |Struct|
+     *            being encoded contains interfaces, can be |null| otherwise.
+     */
+    public Message serialize(Core core) {
+        Encoder encoder = new Encoder(core, mEncodedBaseSize);
+        encode(encoder);
+        return encoder.getMessage();
+    }
+
 }