Allow OSExchangeData::Provider to be overridden at run time.

ui/base/dragdrop/os_exchange_data.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_DRAGDROP_OS_EXCHANGE_DATA_H_
 #define UI_BASE_DRAGDROP_OS_EXCHANGE_DATA_H_
 
 #include <memory>
 #include <set>
 #include <string>
@@ skipping 69 matching lines @@
     scoped_refptr<DownloadFileProvider> downloader;
   };
 
   // Provider defines the platform specific part of OSExchangeData that
   // interacts with the native system.
   class UI_BASE_EXPORT Provider {
    public:
     Provider() {}
     virtual ~Provider() {}
 
-    virtual Provider* Clone() const = 0;
+    virtual std::unique_ptr<Provider> Clone() const = 0;
 
     virtual void MarkOriginatedFromRenderer() = 0;
     virtual bool DidOriginateFromRenderer() const = 0;
 
     virtual void SetString(const base::string16& data) = 0;
     virtual void SetURL(const GURL& url, const base::string16& title) = 0;
     virtual void SetFilename(const base::FilePath& path) = 0;
     virtual void SetFilenames(const std::vector<FileInfo>& file_names) = 0;
     virtual void SetPickledData(const Clipboard::FormatType& format,
                                 const base::Pickle& data) = 0;
@@ skipping 30 matching lines @@
 #endif
 
 #if defined(USE_AURA) || defined(OS_MACOSX)
     virtual void SetDragImage(const gfx::ImageSkia& image,
                               const gfx::Vector2d& cursor_offset) = 0;
     virtual const gfx::ImageSkia& GetDragImage() const = 0;
     virtual const gfx::Vector2d& GetDragImageOffset() const = 0;
 #endif
   };
 
-  // Creates the platform specific Provider.
-  static Provider* CreateProvider();
-
   OSExchangeData();
   // Creates an OSExchangeData with the specified provider. OSExchangeData
   // takes ownership of the supplied provider.
-  explicit OSExchangeData(Provider* provider);
+  explicit OSExchangeData(std::unique_ptr<Provider> provider);
 
   ~OSExchangeData();
 
   // Returns the Provider, which actually stores and manages the data.
   const Provider& provider() const { return *provider_; }
   Provider& provider() { return *provider_; }
 
   // Marks drag data as tainted if it originates from the renderer. This is used
   // to avoid granting privileges to a renderer when dragging in tainted data,
   // since it could allow potential escalation of privileges.
@@ skipping 72 matching lines @@
  private:
   // Provides the actual data.
   std::unique_ptr<Provider> provider_;
 
   DISALLOW_COPY_AND_ASSIGN(OSExchangeData);
 };
 
 }  // namespace ui
 
 #endif  // UI_BASE_DRAGDROP_OS_EXCHANGE_DATA_H_