Mojo C++ bindings: make String16 and gfx::Size available in Blink

third_party/WebKit/Source/platform/mojo/CommonCustomTypesStructTraits.cpp

Index: third_party/WebKit/Source/platform/mojo/CommonCustomTypesStructTraits.cpp
diff --git a/third_party/WebKit/Source/platform/mojo/CommonCustomTypesStructTraits.cpp b/third_party/WebKit/Source/platform/mojo/CommonCustomTypesStructTraits.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..f685a7770b0f72165afced24a37c31c416eadf39
--- /dev/null
+++ b/third_party/WebKit/Source/platform/mojo/CommonCustomTypesStructTraits.cpp
@@ -0,0 +1,38 @@
+// 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 "platform/mojo/CommonCustomTypesStructTraits.h"
+
+#include "mojo/public/cpp/bindings/array_traits_wtf_vector.h"
+#include <cstring>
+
+namespace mojo {
+
+// static
+mojo::ConstCArray<uint16_t>
+StructTraits<mojo::common::mojom::String16DataView, ::WTF::String>::data(
+    const ::WTF::String& str) {
+  DCHECK(!str.isNull())
+      << "mojo::common::mojom::String16 only accepts non-null blink::WebString";
+  DCHECK(!str.is8Bit());
+
+  return mojo::ConstCArray<uint16_t>(str.length(), str.characters16());
+}
+
+// static
+bool StructTraits<mojo::common::mojom::String16DataView, ::WTF::String>::Read(
+    mojo::common::mojom::String16DataView data,
+    ::WTF::String* out) {
+  mojo::ArrayDataView<uint16_t> view;
+  data.GetDataDataView(&view);
+  if (view.is_null())
+    return false;
+  *out =
+      ::WTF::String(reinterpret_cast<const UChar*>(view.data()), view.size());
+  // WTF::String is constructed as 8-bit if the string is empty.
+  out->ensure16Bit();

[Zhiqiang Zhang (Slow), 2016/10/04 20:06:22]

esprehn@, should this be fixed in WTF::String?

I found WTF::String is 8-bit when constructed using WTF::String(UChar*, length)
with length=0, because it calls StringImpl::empty() instead
StringImpl::empty16Bit()

+  return true;
+}
+
+}  // namespace mojo