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

ppapi/cpp/dev/file_chooser_dev.cc

Index: ppapi/cpp/dev/file_chooser_dev.cc
diff --git a/ppapi/cpp/dev/file_chooser_dev.cc b/ppapi/cpp/dev/file_chooser_dev.cc
index ef52b5b06f17cd1d413b29cf3a65c62ece31a59f..7987f48796ce317c2085d7f751eddce7ac7c8827 100644
--- a/ppapi/cpp/dev/file_chooser_dev.cc
+++ b/ppapi/cpp/dev/file_chooser_dev.cc
@@ -8,7 +8,7 @@
 #include "ppapi/c/pp_errors.h"
 #include "ppapi/cpp/completion_callback.h"
 #include "ppapi/cpp/file_ref.h"
-#include "ppapi/cpp/instance.h"
+#include "ppapi/cpp/instance_handle.h"
 #include "ppapi/cpp/module.h"
 #include "ppapi/cpp/module_impl.h"
 
@@ -22,13 +22,13 @@ template <> const char* interface_name<PPB_FileChooser_Dev>() {
 
 }  // namespace
 
-FileChooser_Dev::FileChooser_Dev(const Instance* instance,
+FileChooser_Dev::FileChooser_Dev(const InstanceHandle& instance,
                                  PP_FileChooserMode_Dev mode,
                                  const Var& accept_mime_types) {
   if (!has_interface<PPB_FileChooser_Dev>())
     return;
   PassRefFromConstructor(get_interface<PPB_FileChooser_Dev>()->Create(
-      instance->pp_instance(), mode, accept_mime_types.pp_var()));
+      instance.pp_instance(), mode, accept_mime_types.pp_var()));
 }
 
 FileChooser_Dev::FileChooser_Dev(const FileChooser_Dev& other)
@@ -45,7 +45,7 @@ int32_t FileChooser_Dev::Show(const CompletionCallback& cc) {
 FileRef FileChooser_Dev::GetNextChosenFile() const {
   if (!has_interface<PPB_FileChooser_Dev>())
     return FileRef();
-  return FileRef(FileRef::PassRef(),
+  return FileRef(PASS_REF,
       get_interface<PPB_FileChooser_Dev>()->GetNextChosenFile(pp_resource()));
 }