Add GetSequenceNumber function to PPB_Flash_Clipboard

ppapi/cpp/private/flash_clipboard.cc

Index: ppapi/cpp/private/flash_clipboard.cc
diff --git a/ppapi/cpp/private/flash_clipboard.cc b/ppapi/cpp/private/flash_clipboard.cc
index c63f747bcc073338c4540dde8efc4e81f8fa0562..a1146ffa7b1b38f33866806d7011e07eda094b08 100644
--- a/ppapi/cpp/private/flash_clipboard.cc
+++ b/ppapi/cpp/private/flash_clipboard.cc
@@ -24,13 +24,18 @@ template <> const char* interface_name<PPB_Flash_Clipboard_5_0>() {
   return PPB_FLASH_CLIPBOARD_INTERFACE_5_0;
 }
 
+template <> const char* interface_name<PPB_Flash_Clipboard_5_1>() {
+  return PPB_FLASH_CLIPBOARD_INTERFACE_5_1;
+}
+
 }  // namespace
 
 namespace flash {
 
 // static
 bool Clipboard::IsAvailable() {
-  return has_interface<PPB_Flash_Clipboard_5_0>() ||
+  return has_interface<PPB_Flash_Clipboard_5_1>() ||
+      has_interface<PPB_Flash_Clipboard_5_0>() ||
       has_interface<PPB_Flash_Clipboard_4_0>() ;
 }
 
@@ -148,5 +153,17 @@ bool Clipboard::WriteData(
   return rv;
 }
 
+// static
+bool Clipboard::GetSequenceNumber(const InstanceHandle& instance,
+                                  PP_Flash_Clipboard_Type clipboard_type,
+                                  uint64_t* sequence_number) {
+  if (has_interface<PPB_Flash_Clipboard_5_1>()) {
+    return PP_ToBool(
+        get_interface<PPB_Flash_Clipboard_5_1>()->GetSequenceNumber(
+            instance.pp_instance(), clipboard_type, sequence_number));
+  }
+  return false;
+}
+
 }  // namespace flash
 }  // namespace pp