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

ppapi/cpp/dev/transport_dev.h

Index: ppapi/cpp/dev/transport_dev.h
diff --git a/ppapi/cpp/dev/transport_dev.h b/ppapi/cpp/dev/transport_dev.h
index cf0721e0eb3cc5cf06273d7e65660e2c579e77ac..8545583681e2708b7eb0afa1ac6002e26d16a689 100644
--- a/ppapi/cpp/dev/transport_dev.h
+++ b/ppapi/cpp/dev/transport_dev.h
@@ -11,12 +11,14 @@
 
 namespace pp {
 
-class Instance;
+class InstanceHandle;
 class Var;
 
 class Transport_Dev : public Resource {
  public:
-  Transport_Dev(Instance* instance, const char* name, PP_TransportType type);
+  Transport_Dev(const InstanceHandle& instance,
+                const char* name,
+                PP_TransportType type);
 
   bool IsWritable();
   int32_t SetProperty(PP_TransportProperty property, const Var& value);