Remove internal uses of mojo::Array and mojo::WTFArray.

mojo/public/cpp/bindings/lib/serialization.h

 // Copyright 2016 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.
 
 #ifndef MOJO_PUBLIC_CPP_BINDINGS_LIB_SERIALIZATION_H_
 #define MOJO_PUBLIC_CPP_BINDINGS_LIB_SERIALIZATION_H_
 
 #include <string.h>
 
 #include "mojo/public/cpp/bindings/array_traits_carray.h"
@@ skipping 24 matching lines @@
   size_t size = PrepareToSerialize<MojomType>(*input, &context);
   DCHECK_EQ(size, Align(size));
 
   DataArrayType result(size);
   if (size == 0)
     return result;
 
   void* result_buffer = &result.front();
   // The serialization logic requires that the buffer is 8-byte aligned. If the
   // result buffer is not properly aligned, we have to do an extra copy. In
-  // practice, this should never happen for mojo::Array (backed by std::vector).
+  // practice, this should never happen for std::vector.
   bool need_copy = !IsAligned(result_buffer);
 
   if (need_copy) {
     // calloc sets the memory to all zero.
     result_buffer = calloc(size, 1);
     DCHECK(IsAligned(result_buffer));
   }
 
   Buffer buffer;
   buffer.Initialize(result_buffer, size);
   typename MojomTypeTraits<MojomType>::Data* data = nullptr;
   Serialize<MojomType>(*input, &buffer, &data, &context);
 
   if (need_copy) {
     memcpy(&result.front(), result_buffer, size);
     free(result_buffer);
   }
 
   return result;
 }
 
 template <typename MojomType, typename DataArrayType, typename UserType>
 bool StructDeserializeImpl(const DataArrayType& input, UserType* output) {
   static_assert(BelongsTo<MojomType, MojomTypeCategory::STRUCT>::value,
                 "Unexpected type.");
   using DataType = typename MojomTypeTraits<MojomType>::Data;
 
-  if (input.is_null())
-    return false;
-
+  // TODO(sammc): Use DataArrayType::empty() once WTF::Vector::empty() exists.
   void* input_buffer =
-      input.empty()
+      input.size() == 0
           ? nullptr
           : const_cast<void*>(reinterpret_cast<const void*>(&input.front()));
 
   // Please see comments in StructSerializeImpl.
   bool need_copy = !IsAligned(input_buffer);
 
   if (need_copy) {
     input_buffer = malloc(input.size());
     DCHECK(IsAligned(input_buffer));
     memcpy(input_buffer, &input.front(), input.size());
@@ skipping 10 matching lines @@
   if (need_copy)
     free(input_buffer);
 
   return result;
 }
 
 }  // namespace internal
 }  // namespace mojo
 
 #endif  // MOJO_PUBLIC_CPP_BINDINGS_LIB_SERIALIZATION_H_