Mojo C++ bindings: expose public <struct>DataView and StringDataView.

mojo/public/cpp/bindings/lib/string_traits_wtf.cc

 // 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.
 
 #include "mojo/public/cpp/bindings/string_traits_wtf.h"
 
 #include <string.h>
 
 #include "base/logging.h"
 #include "mojo/public/cpp/bindings/lib/array_internal.h"
@@ skipping 48 matching lines @@
   return ToAdaptor(input, context)->utf8_adaptor.length();
 }
 
 // static
 const char* StringTraits<WTF::String>::GetData(const WTF::String& input,
                                                void* context) {
   return ToAdaptor(input, context)->utf8_adaptor.data();
 }
 
 // static
-bool StringTraits<WTF::String>::Read(internal::String_Data* input,
+bool StringTraits<WTF::String>::Read(StringDataView input,
                                      WTF::String* output) {
-  if (input) {
-    WTF::String result = WTF::String::fromUTF8(input->storage(), input->size());
+  if (!input.is_null()) {
+    WTF::String result = WTF::String::fromUTF8(input.storage(), input.size());
     output->swap(result);
   } else if (!output->isNull()) {
     WTF::String result;
     output->swap(result);
   }
   return true;
 }
 
 }  // namespace mojo