mojo: Add maps to java bindings.

mojo/public/java/bindings/src/org/chromium/mojo/bindings/BindingsHelper.java

Index: mojo/public/java/bindings/src/org/chromium/mojo/bindings/BindingsHelper.java
diff --git a/mojo/public/java/bindings/src/org/chromium/mojo/bindings/BindingsHelper.java b/mojo/public/java/bindings/src/org/chromium/mojo/bindings/BindingsHelper.java
index b18e5c54c5b0fef01f1bc2ef1b4b8fc81f0e2fd9..d97547fbeac1b6b18872bbb4279d35bb44a180c6 100644
--- a/mojo/public/java/bindings/src/org/chromium/mojo/bindings/BindingsHelper.java
+++ b/mojo/public/java/bindings/src/org/chromium/mojo/bindings/BindingsHelper.java
@@ -4,6 +4,7 @@
 
 package org.chromium.mojo.bindings;
 
+import org.chromium.mojo.bindings.Struct.DataHeader;
 import org.chromium.mojo.system.AsyncWaiter;
 import org.chromium.mojo.system.Handle;
 
@@ -29,16 +30,14 @@ public class BindingsHelper {
     public static final int POINTER_SIZE = 8;
 
     /**
-     * The value used for the expected length of a non-fixed size array.
+     * The header for a serialized map element.
      */
-    public static final int UNSPECIFIED_ARRAY_LENGTH = -1;
+    public static final DataHeader MAP_STRUCT_HEADER = new DataHeader(24, 2);
 
     /**
-     * Align |size| on {@link BindingsHelper#ALIGNMENT}.
+     * The value used for the expected length of a non-fixed size array.
      */
-    public static int align(int size) {
-        return (size + ALIGNMENT - 1) & ~(ALIGNMENT - 1);
-    }
+    public static final int UNSPECIFIED_ARRAY_LENGTH = -1;
 
     /**
      * Passed as |arrayNullability| when neither the array nor its elements are nullable.
@@ -66,6 +65,13 @@ public class BindingsHelper {
     /**
      * Align |size| on {@link BindingsHelper#ALIGNMENT}.
      */
+    public static int align(int size) {
+        return (size + ALIGNMENT - 1) & ~(ALIGNMENT - 1);
+    }
+
+    /**
+     * Align |size| on {@link BindingsHelper#ALIGNMENT}.
+     */
     public static long align(long size) {
         return (size + ALIGNMENT - 1) & ~(ALIGNMENT - 1);
     }