Rewrite clipboard write IPC handling to be easier to understand.

content/renderer/renderer_clipboard_client.h

-// Copyright (c) 2012 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_RENDERER_RENDERER_CLIPBOARD_CLIENT_H_
-#define CONTENT_RENDERER_RENDERER_CLIPBOARD_CLIENT_H_
-
-#include "base/compiler_specific.h"
-#include "content/renderer/clipboard_client.h"
-
-namespace content {
-
-// An implementation of ClipboardClient that gets and sends data over IPC.
-class RendererClipboardClient : public ClipboardClient {
- public:
-  RendererClipboardClient();
-  ~RendererClipboardClient() override;
-
-  ui::Clipboard* GetClipboard() override;
-  uint64 GetSequenceNumber(ui::ClipboardType type) override;
-  bool IsFormatAvailable(ClipboardFormat format,
-                         ui::ClipboardType type) override;
-  void Clear(ui::ClipboardType type) override;
-  void ReadAvailableTypes(ui::ClipboardType type,
-                          std::vector<base::string16>* types,
-                          bool* contains_filenames) override;
-  void ReadText(ui::ClipboardType type, base::string16* result) override;
-  void ReadHTML(ui::ClipboardType type,
-                base::string16* markup,
-                GURL* url,
-                uint32* fragment_start,
-                uint32* fragment_end) override;
-  void ReadRTF(ui::ClipboardType type, std::string* result) override;
-  void ReadImage(ui::ClipboardType type, std::string* data) override;
-  void ReadCustomData(ui::ClipboardType clipboard_type,
-                      const base::string16& type,
-                      base::string16* data) override;
-  WriteContext* CreateWriteContext() override;
-};
-
-}  // namespace content
-
-#endif  // CONTENT_RENDERER_RENDERER_CLIPBOARD_CLIENT_H_