Move flash clipboard to the new proxy and add custom format support

ppapi/cpp/private/flash_clipboard.h

Index: ppapi/cpp/private/flash_clipboard.h
diff --git a/ppapi/cpp/private/flash_clipboard.h b/ppapi/cpp/private/flash_clipboard.h
index 2894c8f3f074d58dbc45ccf5d0e3d31a898cd701..aab06efb1e91a67f5f81fb392c2d47121ce09510 100644
--- a/ppapi/cpp/private/flash_clipboard.h
+++ b/ppapi/cpp/private/flash_clipboard.h
@@ -22,23 +22,28 @@ class Clipboard {
   // Returns true if the required interface is available.
   static bool IsAvailable();
 
+  // Returns a format ID on success or PP_FLASH_CLIPBOARD_FORMAT_INVALID on
+  // failure.
+  static uint32_t RegisterCustomFormat(const InstanceHandle& instance,
+                                       const std::string& format_name);
+
   // Returns true if the given format is available from the given clipboard.
   static bool IsFormatAvailable(const InstanceHandle& instance,
                                 PP_Flash_Clipboard_Type clipboard_type,
-                                PP_Flash_Clipboard_Format format);
+                                uint32_t format);
 
   // Returns true on success, in which case |out| will be filled with
   // data read from the given clipboard in the given format.
   static bool ReadData(const InstanceHandle& instance,
                        PP_Flash_Clipboard_Type clipboard_type,
-                       PP_Flash_Clipboard_Format clipboard_format,
+                       uint32_t clipboard_format,
                        Var* out);
 
   // Returns true on success in which case all of |data| will be written to
   // the clipboard. Otherwise nothing will be written.
   static bool WriteData(const InstanceHandle& instance,
                         PP_Flash_Clipboard_Type clipboard_type,
-                        const std::vector<PP_Flash_Clipboard_Format>& formats,
+                        const std::vector<uint32_t>& formats,
                         const std::vector<Var>& data_items);
 };