Tweaks to PPB_VarArrayBuffer in preperation for taking out of Dev.

ppapi/tests/test_post_message.cc

Index: ppapi/tests/test_post_message.cc
diff --git a/ppapi/tests/test_post_message.cc b/ppapi/tests/test_post_message.cc
index 6051e30c58768ff49944b9256b997c6df4199d63..64faef0ef2a20ee061fffb25b433ebb2a72a924e 100644
--- a/ppapi/tests/test_post_message.cc
+++ b/ppapi/tests/test_post_message.cc
@@ -263,8 +263,15 @@ std::string TestPostMessage::TestSendingArrayBuffer() {
     pp::VarArrayBuffer_Dev test_data(sizes[i]);
     if (sizes[i] > 0)
       ASSERT_NE(NULL, test_data.Map());
+    // Make sure we can Unmap/Map successfully (there's not really any way to
+    // detect if it's unmapped, so we just re-map before getting the pointer to
+    // the buffer).
+    test_data.Unmap();
+    test_data.Map();
     ASSERT_EQ(sizes[i], test_data.ByteLength());
     unsigned char* buff = static_cast<unsigned char*>(test_data.Map());
+    test_data.Unmap();
+    test_data.Map();
     const uint32_t kByteLength = test_data.ByteLength();
     for (size_t j = 0; j < kByteLength; ++j)
       buff[j] = static_cast<uint8_t>(j % 256u);