Add mojo struct traits for GURL so that it can be sent over mojoms.

url/mojo/url_gurl.h

+// Copyright 2016 The Chromium Authors. All rights reserved.

[dcheng, 2016/03/03 16:23:53]

Can we have some sort of naming convention for files that have StructTraits (and
maybe TypeConverters?) like we do for IPC::ParamTraits? url_struct_traits.*
maybe?

[jam, 2016/03/03 21:25:12]

sure that seems reasonable, renamed

+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/strings/string_piece.h"
+#include "url/gurl.h"
+#include "url/mojo/url.mojom.h"
+
+namespace mojo {
+
+// copied from content/public/common/content_constants.cc: make that file use
+// this definition.
+const size_t kMaxURLChars = 2 * 1024 * 1024;

[dcheng, 2016/03/03 16:23:53]

Nit: Strictly speaking, this should be kMaxUrlChars now =/

[jam, 2016/03/03 21:25:12]

Done.

+
+template <>
+struct StructTraits<url::mojom::Url, GURL> {
+  static base::StringPiece url(const GURL& r) {

[dcheng, 2016/03/03 16:23:53]

Is there documentation on how StructTraits work? How does stuff that deduce the
type know that it needs to call StructTraits<T, U>::url() and not
StructTraits<T, U>::string()? Or am I completely misunderstanding how this
works?

[jam, 2016/03/03 21:25:12]

Looks like Ken already replied.

+    if (r.possibly_invalid_spec().length() > kMaxURLChars || !r.is_valid()) {
+      return base::StringPiece();
+    }
+
+    return base::StringPiece(r.possibly_invalid_spec().c_str(),
+                             r.possibly_invalid_spec().length());
+  }
+  static bool Read(url::mojom::Url::Reader r, GURL* out) {
+    if (r.url().length() > kMaxURLChars) {
+      *out = GURL();
+      return false;
+    }
+    *out = GURL(r.url());
+    if (!r.url().empty() && !out->is_valid()) {
+      *out = GURL();
+      return false;
+    }
+    return true;
+  }
+};
+
+}