Change all platforms except Windows to access the clipboard solely from the UI thread

ui/base/clipboard/clipboard.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 UI_BASE_CLIPBOARD_CLIPBOARD_H_
 #define UI_BASE_CLIPBOARD_CLIPBOARD_H_
 #pragma once
 
 #include <map>
 #include <string>
 #include <vector>
 
 #include "base/gtest_prod_util.h"
 #include "base/process.h"
 #include "base/shared_memory.h"
 #include "base/string16.h"
+#include "base/threading/thread_checker.h"
 #include "ui/base/ui_export.h"
 
 #if defined(TOOLKIT_USES_GTK)
 #include <gdk/gdk.h>
 #endif
 
 namespace gfx {
 class Size;
 }
 
 class FilePath;
 class SkBitmap;
 
 #if defined(TOOLKIT_USES_GTK)
 typedef struct _GtkClipboard GtkClipboard;
 #endif
 
 #ifdef __OBJC__
 @class NSString;
 #else
 class NSString;
 #endif
 
 namespace ui {
 
-class UI_EXPORT Clipboard {
+class UI_EXPORT Clipboard : public base::ThreadChecker {
  public:
   // Platform neutral holder for native data representation of a clipboard type.
   struct UI_EXPORT FormatType {
     FormatType();
     ~FormatType();
 
     std::string Serialize() const;
     static FormatType Deserialize(const std::string& serialization);
 
    private:
@@ skipping 148 matching lines @@
   void ReadCustomData(Buffer buffer,
                       const string16& type,
                       string16* result) const;
 
   // Reads a bookmark from the clipboard, if available.
   void ReadBookmark(string16* title, std::string* url) const;
 
   // Reads a file or group of files from the clipboard, if available, into the
   // out parameter.
   void ReadFile(FilePath* file) const;
-  void ReadFiles(std::vector<FilePath>* files) const;
 
   // Reads raw data from the clipboard with the given format type. Stores result
   // as a byte vector.
   void ReadData(const FormatType& format, std::string* result) const;
 
   // Gets the FormatType corresponding to an arbitrary format string,
   // registering it with the system if needed. Due to Windows/Linux
   // limitiations, |format_string| must never be controlled by the user.
   static FormatType GetFormatType(const std::string& format_string);
 
@@ skipping 24 matching lines @@
   static const FormatType& GetTextHtmlFormatType();
   static const FormatType& GetCFHDropFormatType();
   static const FormatType& GetFileDescriptorFormatType();
   static const FormatType& GetFileContentFormatZeroType();
 #endif
 
  private:
   FRIEND_TEST_ALL_PREFIXES(ClipboardTest, SharedBitmapTest);
   FRIEND_TEST_ALL_PREFIXES(ClipboardTest, EmptyHTMLTest);
 
+  void ReadFiles(std::vector<FilePath>* files) const;
+
   void DispatchObject(ObjectType type, const ObjectMapParams& params);
 
   void WriteText(const char* text_data, size_t text_len);
 
   void WriteHTML(const char* markup_data,
                  size_t markup_len,
                  const char* url_data,
                  size_t url_len);
 
   void WriteBookmark(const char* title_data,
@@ skipping 61 matching lines @@
   static const char kMimeTypeText[];
   static const char kMimeTypeHTML[];
   static const char kMimeTypePNG[];
 
   DISALLOW_COPY_AND_ASSIGN(Clipboard);
 };
 
 }  // namespace ui
 
 #endif  // UI_BASE_CLIPBOARD_CLIPBOARD_H_