Convert MimeRegistry to use mojo.

content/browser/mime_registry_impl.cc

+// Copyright (c) 2011 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 "content/browser/mime_registry_impl.h"
+
+#include "base/files/file_path.h"
+#include "content/public/browser/browser_thread.h"
+#include "mojo/common/common_type_converters.h"
+#include "net/base/mime_util.h"
+
+namespace content {
+
+// static
+void MimeRegistryImpl::Create(blink::mojom::MimeRegistryRequest request) {
+  DCHECK_CURRENTLY_ON(BrowserThread::FILE);
+  new MimeRegistryImpl(std::move(request));
+}
+
+MimeRegistryImpl::MimeRegistryImpl(blink::mojom::MimeRegistryRequest request)
+    : binding_(this, std::move(request)) {}
+
+MimeRegistryImpl::~MimeRegistryImpl() = default;
+
+void MimeRegistryImpl::GetMimeTypeFromExtension(
+    const mojo::String& extension,
+    const GetMimeTypeFromExtensionCallback& callback) {

[nasko, 2016/06/02 21:31:41]

nit: Since this is expected to be invoked on the FILE thread, why not add a
DCHECK_CURRENTLY_ON?

[Sam McNally, 2016/06/02 23:49:39]

Done.

+  std::string mime_type;
+  net::GetMimeTypeFromExtension(extension.To<base::FilePath::StringType>(),
+                                &mime_type);
+  callback.Run(mime_type);
+}
+
+}  // namespace content