[MD settings] i18n source stream filtering

content/browser/webui/i18n_source_stream.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 CONTENT_BROWSER_WEBUI_I18N_SOURCE_STREAM_H_
+#define CONTENT_BROWSER_WEBUI_I18N_SOURCE_STREAM_H_
+
+#include <memory>
+#include <string>
+
+#include "base/macros.h"
+#include "content/common/content_export.h"
+#include "net/filter/filter_source_stream.h"
+#include "ui/base/template_expressions.h"
+
+namespace content {
+
+class CONTENT_EXPORT I18nSourceStream : public net::FilterSourceStream {
+ public:
+  ~I18nSourceStream() override;
+
+  // Factory function to create an I18nSourceStream.
+  // |replacements| is a dictionary of i18n replacements.
+  static std::unique_ptr<I18nSourceStream> Create(
+      std::unique_ptr<SourceStream> previous,
+      SourceStream::SourceType type,
+      const ui::TemplateReplacements* replacements);
+
+ private:
+  I18nSourceStream(std::unique_ptr<SourceStream> previous,
+                   SourceStream::SourceType type,
+                   const ui::TemplateReplacements* replacements);
+
+  // SourceStream implementation.
+  std::string GetTypeAsString() const override;
+  int FilterData(net::IOBuffer* output_buffer,
+                 int output_buffer_size,
+                 net::IOBuffer* input_buffer,
+                 int input_buffer_size,
+                 int* consumed_bytes,
+                 bool upstream_end_reached) override;
+
+  // Accumulated from upstream.
+  std::string input_;
+
+  // To send downstream.
+  std::string output_;
+
+  // How much of the |output_| has been sent.
+  size_t drain_offset_;
+
+  // A map of i18n replacement keys and translations.
+  const ui::TemplateReplacements* replacements_;  // weak
+
+  DISALLOW_COPY_AND_ASSIGN(I18nSourceStream);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_WEBUI_I18N_SOURCE_STREAM_H_