Revert of Rewrite clipboard write IPC handling to be easier to understand.

ui/base/test/test_clipboard.h

 // Copyright 2014 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_TEST_TEST_CLIPBOARD_H_
 #define UI_BASE_TEST_TEST_CLIPBOARD_H_
 
 #include <map>
 #include "third_party/skia/include/core/SkBitmap.h"
 #include "ui/base/clipboard/clipboard.h"
 
 namespace ui {
 
 class TestClipboard : public Clipboard {
  public:
   TestClipboard();
   ~TestClipboard() override;
 
-  // Creates and associates a TestClipboard with the current thread. When no
-  // longer needed, the returned clipboard must be freed by calling
-  // Clipboard::DestroyClipboardForCurrentThread() on the same thread.
-  static Clipboard* CreateForCurrentThread();
+  static void UseForCurrentThread();
 
   // Clipboard overrides.
   uint64 GetSequenceNumber(ClipboardType type) const override;
   bool IsFormatAvailable(const FormatType& format,
                          ClipboardType type) const override;
   void Clear(ClipboardType type) override;
   void ReadAvailableTypes(ClipboardType type,
                           std::vector<base::string16>* types,
                           bool* contains_filenames) const override;
   void ReadText(ClipboardType type, base::string16* result) const override;
@@ skipping 47 matching lines @@
 
   ClipboardType default_store_type_;
   mutable std::map<ClipboardType, DataStore> stores_;
 
   DISALLOW_COPY_AND_ASSIGN(TestClipboard);
 };
 
 }  // namespace ui
 
 #endif  // UI_BASE_TEST_TEST_CLIPBOARD_H_