Pepper/Flapper: Add IsFormatAvailable() to PPB_Flash_Clipboard.

ppapi/c/private/ppb_flash_clipboard.h

 // Copyright (c) 2011 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 PPAPI_C_PRIVATE_PPB_FLASH_CLIPBOARD_H_
 #define PPAPI_C_PRIVATE_PPB_FLASH_CLIPBOARD_H_
 
+#include "ppapi/c/pp_bool.h"
 #include "ppapi/c/pp_instance.h"
 #include "ppapi/c/pp_var.h"
 
-#define PPB_FLASH_CLIPBOARD_INTERFACE "PPB_Flash_Clipboard;2"
+#define PPB_FLASH_CLIPBOARD_INTERFACE "PPB_Flash_Clipboard;3"
 
 typedef enum {
   PP_FLASH_CLIPBOARD_TYPE_STANDARD = 0,
   PP_FLASH_CLIPBOARD_TYPE_SELECTION = 1,
   PP_FLASH_CLIPBOARD_TYPE_DRAG = 2
 } PP_Flash_Clipboard_Type;
 
+typedef enum {
+  PP_FLASH_CLIPBOARD_FORMAT_INVALID = 0,
+  PP_FLASH_CLIPBOARD_FORMAT_PLAINTEXT = 1,
+  PP_FLASH_CLIPBOARD_FORMAT_HTML = 2
+} PP_Flash_Clipboard_Format;
+
 struct PPB_Flash_Clipboard {
+  // Returns true if the given format is available from the given clipboard.
+  PP_Bool (*IsFormatAvailable)(PP_Instance instance_id,
+                               PP_Flash_Clipboard_Type clipboard_type,
+                               PP_Flash_Clipboard_Format format);
+
   // Reads plain text data from the clipboard.
   struct PP_Var (*ReadPlainText)(PP_Instance instance_id,
                                  PP_Flash_Clipboard_Type clipboard_type);
 
   // Writes plain text data to the clipboard. If |text| is too large, it will
   // return |PP_ERROR_NOSPACE| (and not write to the clipboard).
   int32_t (*WritePlainText)(PP_Instance instance_id,
                             PP_Flash_Clipboard_Type clipboard_type,
                             struct PP_Var text);
 
-  // TODO(vtl): More formats, a |IsFormatAvailable()|, ....
+  // TODO(vtl): More formats (e.g., HTML)....
 };
 
 #endif  // PPAPI_C_PRIVATE_PPB_FLASH_CLIPBOARD_H_