[Mojo] Improve JavaScript API for MojoReadMessage

mojo/public/bindings/js/core_unittests.js

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 define([
     "gtest",
     "mojo/public/bindings/js/core",
   ], function(gtest, core) {
   runWithPipe(testNop);
   runWithPipe(testReadAndWriteMessage);
@@ skipping 24 matching lines @@
 
     var result = core.writeMessage(
       pipe.handle0, senderData, [],
       core.WRITE_MESSAGE_FLAG_NONE);
 
     gtest.expectEqual(result, core.RESULT_OK,
       "writeMessage returned RESULT_OK: " + result);
 
     var receiverData = new Uint8Array(50);
 
-    var mesage = core.readMessage(
-      pipe.handle1, receiverData, 10,
-      core.READ_MESSAGE_FLAG_NONE)
+    var read = core.readMessage(
+      pipe.handle1, core.READ_MESSAGE_FLAG_NONE)
 
-    gtest.expectEqual(mesage.result, core.RESULT_OK,
-        "mesage.result is " + mesage.result);
-    gtest.expectEqual(mesage.bytesRead, 42,
-        "mesage.bytesRead is " + mesage.bytesRead);
-    gtest.expectEqual(mesage.handles.length, 0,
-        "mesage.handles.length is " + mesage.handles.length);
+    gtest.expectEqual(read.result, core.RESULT_OK,
+        "read.result is " + read.result);
+    gtest.expectEqual(read.buffer.byteLength, 42,
+        "read.buffer.byteLength is " + read.buffer.byteLength);
+    gtest.expectEqual(read.handles.length, 0,
+        "read.handles.length is " + read.handles.length);
 
-    for (var i = 0; i < mesage.bytesRead; ++i) {
-      gtest.expectEqual(receiverData[i], (i * i) & 0xFF,
-          "receiverData[" + i + "] is " + receiverData[i]);
+    var memory = new Uint8Array(read.buffer);
+    for (var i = 0; i < memory.length; ++i) {
+      gtest.expectEqual(memory[i], (i * i) & 0xFF,
+          "memory[" + i + "] is " + memory[i]);
     }
   }
 });