Refactor PPAPI proxy resource handling to maintain which host they came from,...

ppapi/proxy/host_resource.h

+// Copyright (c) 2011 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_PROXY_HOST_RESOURCE_H_
+#define PPAPI_PROXY_HOST_RESOURCE_H_
+
+#include "ppapi/c/pp_instance.h"
+#include "ppapi/c/pp_resource.h"
+
+namespace pp {
+namespace proxy {
+
+// Represents a PP_Resource sent over the wire. This just wraps a PP_Resource.
+// The point is to prevent mistakes where the wrong resource value is sent.
+// Resource values are remapped in the plugin so that it can talk to multiple
+// hosts. If all values were PP_Resource, it would be easy to forget to do
+// this tranformation.
+//
+// All HostResources respresent IDs valid in the host.
+class HostResource {
+ public:
+  HostResource() : instance_(0), host_resource_(0) {
+  }
+
+  bool is_null() const {
+    return !host_resource_;
+  }
+
+  // Sets and retrieves the internal PP_Resource which is valid for the host
+  // (a.k.a. renderer, as opposed to the plugin) process.
+  //
+  // DO NOT CALL THESE FUNCTIONS IN THE PLUGIN SIDE OF THE PROXY. The values
+  // will be invalid. See the class comment above.
+  void SetHostResource(PP_Instance instance, PP_Resource resource) {
+    instance_ = instance;
+    host_resource_ = resource;
+  }
+  PP_Resource host_resource() const {
+    return host_resource_;
+  }
+
+  PP_Instance instance() const { return instance_; }
+
+  // This object is used in maps so we need to provide this sorting operator.
+  bool operator<(const HostResource& other) const {
+    if (instance_ != other.instance_)
+      return instance_ < other.instance_;
+    return host_resource_ < other.host_resource_;
+  }
+
+ private:
+  PP_Instance instance_;
+  PP_Resource host_resource_;
+};
+
+}  // namespace proxy
+}  // namespace pp
+
+#endif  // PPAPI_PROXY_HOST_RESOURCE_H_