Convert resources to take an instance key instead of an Instance*.

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 db13ce67c8d1952e883d35330eed45576bfc9d9e..11e7571a615f5d622c16e569575a28f938ac8717 100644
--- a/ppapi/cpp/private/flash_clipboard.h
+++ b/ppapi/cpp/private/flash_clipboard.h
@@ -11,7 +11,7 @@
 
 namespace pp {
 
-class Instance;
+class InstanceHandle;
 
 namespace flash {
 
@@ -21,18 +21,18 @@ class Clipboard {
   static bool IsAvailable();
 
   // Returns true if the given format is available from the given clipboard.
-  static bool IsFormatAvailable(Instance* instance,
+  static bool IsFormatAvailable(const InstanceHandle& instance,
                                 PP_Flash_Clipboard_Type clipboard_type,
                                 PP_Flash_Clipboard_Format format);
 
   // Returns true on success, in which case |text_out| will be filled with plain
   // text read from the given clipboard.
-  static bool ReadPlainText(Instance* instance,
+  static bool ReadPlainText(const InstanceHandle& instance,
                             PP_Flash_Clipboard_Type clipboard_type,
                             std::string* text_out);
 
   // Returns true on success (it may fail if |text| is too big).
-  static bool WritePlainText(Instance* instance,
+  static bool WritePlainText(const InstanceHandle& instance,
                              PP_Flash_Clipboard_Type clipboard_type,
                              const std::string& text);
 };