Implement the file chooser as a new resource "host"

ppapi/proxy/plugin_resource.h

Index: ppapi/proxy/plugin_resource.h
diff --git a/ppapi/proxy/plugin_resource.h b/ppapi/proxy/plugin_resource.h
new file mode 100644
index 0000000000000000000000000000000000000000..d43179ed2d64818a18b500ef0f629ccd3895fb7c
--- /dev/null
+++ b/ppapi/proxy/plugin_resource.h
@@ -0,0 +1,64 @@
+// Copyright (c) 2012 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_PLUGIN_RESOURCE_H_
+#define PPAPI_PROXY_PLUGIN_RESOURCE_H_
+
+#include "base/compiler_specific.h"
+#include "ipc/ipc_sender.h"
+#include "ppapi/proxy/ppapi_proxy_export.h"
+#include "ppapi/shared_impl/resource.h"
+
+namespace IPC {
+class Message;
+}
+
+namespace ppapi {
+namespace proxy {
+
+class PluginDispatcher;
+
+class PPAPI_PROXY_EXPORT PluginResource : public Resource,
+                                          public IPC::Sender {
+ public:
+  PluginResource(IPC::Sender* sender,
+                 PP_Instance instance);
+  virtual ~PluginResource();
+
+  // IPC::Sender implementation.
+  virtual bool Send(IPC::Message* message) OVERRIDE;
+
+  bool sent_create_to_renderer() const { return sent_create_to_renderer_; }
+
+ protected:
+  // Sends a create message to the renderer for the current resource.
+  void SendCreateToRenderer(const IPC::Message& msg);
+
+  // Sends the given IPC message as a resource request to the host
+  // corresponding to this resource object and does not expect a reply.
+  void PostToRenderer(const IPC::Message& msg);
+
+  // Like PostToRenderer but expects a response.
+  //
+  // Returns the new request's sequence number which can be used to identify
+  // the callback. The host will reply and ppapi::Resource::OnReplyReceived
+  // will be called.
+  //
+  // Note that all integers (including 0 and -1) are valid request IDs.
+  int32_t CallRenderer(const IPC::Message& msg);

[bbudge, 2012/07/02 20:06:06]

It seems odd that sequence numbers are signed ints.

[brettw, 2012/07/07 05:28:04]

Well, it's going to theoretically wrap anyway (so it doesn't matter) and the
style guide says to use signed values except for bitfields, so I went with
signed.

+
+ private:
+  IPC::Sender* sender_;
+
+  int next_sequence_number_;

[bbudge, 2012/07/02 20:06:06]

int -> int32_t or uint32_t?

+
+  bool sent_create_to_renderer_;
+
+  DISALLOW_COPY_AND_ASSIGN(PluginResource);
+};
+
+}  // namespace proxy
+}  // namespace ppapi
+
+#endif  // PPAPI_PROXY_PLUGIN_RESOURCE_H_