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

ppapi/cpp/dev/selection_dev.h

 // Copyright (c) 2010 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_CPP_DEV_SELECTION_DEV_H_
 #define PPAPI_CPP_DEV_SELECTION_DEV_H_
 
 #include "ppapi/c/dev/ppp_selection_dev.h"
+#include "ppapi/cpp/instance_handle.h"
 
 namespace pp {
 
-class Instance;
 class Var;
 
 // This class allows you to associate the PPP_Selection_Dev C-based interface
 // with an object. It registers as the global handler for handling the
 // PPP_Selection_Dev interface that the browser calls.
 //
 // You would typically use this either via inheritance on your instance:
 //   class MyInstance : public pp::Instance, public pp::Selection_Dev {
 //     class MyInstance() : pp::Selection_Dev(this) {
 //     }
 //     ...
 //   };
 //
 // or by composition:
 //   class MySelection : public pp::Selection_Dev {
 //     ...
 //   };
 //
 //   class MyInstance : public pp::Instance {
 //     MyInstance() : selection_(this) {
 //     }
 //
 //     MySelection selection_;
 //   };
 class Selection_Dev {
  public:
-  Selection_Dev(Instance* instance);
+  explicit Selection_Dev(const InstanceHandle& instance);
   virtual ~Selection_Dev();
 
   // PPP_Selection_Dev functions exposed as virtual functions for you to
   // override.
   virtual Var GetSelectedText(bool html) = 0;
 
  private:
-  Instance* associated_instance_;
+  InstanceHandle associated_instance_;
 };
 
 }  // namespace pp
 
 #endif  // PPAPI_CPP_DEV_SELECTION_DEV_H_