Implement URL and Origin typemaps/struct traits for blink.

third_party/WebKit/Source/platform/mojo/KURLStructTraits.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 KURLStructTraits_h
+#define KURLStructTraits_h
+
+#include "platform/weborigin/KURL.h"
+#include "url/mojo/url.mojom-blink.h"
+#include "url/url_constants.h"
+
+namespace mojo {
+
+template <>
+struct StructTraits<url::mojom::blink::Url, blink::KURL> {

[Ken Rockot(use gerrit already), 2016/05/25 15:09:20]

You will need to qualify blink::KURL here for now. This is unfortunate, and it's
a result of the fact that we generate some bindings (for internal control
messages) in the mojo:: namespace. The blink variant of those introduces a
mojo::blink namespace.

We can move them to mojo::internal to avoid stuff like this in the future.

[yzshen1, 2016/05/25 16:43:14]

Ah, that seems unfortunate. Moving those things into mojo::internal will require
fixing some bindings code/template, because we already have mojo::internal::
defined, too. The easiest way is to move them into something like
mojo.interface_control (we already have mojo.pipe_control for some other control
messages).

+    static WTF::String url(const blink::KURL& r)
+    {
+        if (!r.isValid() || r.getString().length() > url::kMaxURLChars) {
+            return emptyString();
+        }
+
+        return r.getString();
+    }
+    static bool Read(url::mojom::blink::UrlDataView data, blink::KURL* out)
+    {
+        WTF::String urlString;
+        if (!data.ReadUrl(&urlString))
+            return false;
+
+        if (urlString.length() > url::kMaxURLChars)
+            return false;
+
+        *out = blink::KURL(blink::KURL(), urlString);
+        if (!urlString.isEmpty() && !out->isValid())
+            return false;
+
+        return true;
+    }
+};
+}
+
+#endif // KURLStructTraits_h