Implement the file chooser as a new resource "host"

ppapi/host/dispatch_host_message.h

Index: ppapi/host/dispatch_host_message.h
diff --git a/ppapi/host/dispatch_host_message.h b/ppapi/host/dispatch_host_message.h
new file mode 100644
index 0000000000000000000000000000000000000000..3e60e577995811528325215c36fcc42acfae1f0a
--- /dev/null
+++ b/ppapi/host/dispatch_host_message.h
@@ -0,0 +1,78 @@
+// 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.
+
+#include "ipc/ipc_message_macros.h"
+
+// This file provides infrastructure for dispatching host resource call
+// messages. Normal IPC message handlers can't take extra parameters or
+// return values. We want to take a HostMessageContext as a parameter and
+// also return the int32_t return value to the caller.
+
+#include "base/profiler/scoped_profile.h"  // For TRACK_RUN_IN_IPC_HANDLER.
+#include "ppapi/c/pp_errors.h"
+
+namespace ppapi {
+namespace host {
+
+struct HostMessageContext;
+
+template <class ObjT, class Method>
+inline int32_t DispatchResourceCall(ObjT* obj, Method method,
+                                    HostMessageContext* context,
+                                    const Tuple0& arg) {
+  return (obj->*method)(context);
+}
+
+template <class ObjT, class Method, class A>
+inline int32_t DispatchResourceCall(ObjT* obj, Method method,
+                                    HostMessageContext* context,
+                                    const Tuple1<A>& arg) {
+  return (obj->*method)(context, arg.a);
+}
+
+template<class ObjT, class Method, class A, class B>
+inline int32_t DispatchResourceCall(ObjT* obj, Method method,
+                                    HostMessageContext* context,
+                                    const Tuple2<A, B>& arg) {
+  return (obj->*method)(context, arg.a, arg.b);
+}
+
+template<class ObjT, class Method, class A, class B, class C>
+inline int32_t DispatchResourceCall(ObjT* obj, Method method,
+                                    HostMessageContext* context,
+                                    const Tuple3<A, B, C>& arg) {
+  return (obj->*method)(context, arg.a, arg.b, arg.c);
+}
+
+template<class ObjT, class Method, class A, class B, class C, class D>
+inline int32_t DispatchResourceCall(ObjT* obj, Method method,
+                                    HostMessageContext* context,
+                                    const Tuple4<A, B, C, D>& arg) {
+  return (obj->*method)(context, arg.a, arg.b, arg.c, arg.d);
+}
+
+template<class ObjT, class Method, class A, class B, class C, class D, class E>
+inline int32_t DispatchResourceCall(ObjT* obj, Method method,
+                                    HostMessageContext* context,
+                                    const Tuple5<A, B, C, D, E>& arg) {
+  return (obj->*method)(context, arg.a, arg.b, arg.c, arg.d, arg.e);
+}
+
+#define PPAPI_DISPATCH_HOST_RESOURCE_CALL(msg_class, member_func) \
+    case msg_class::ID: { \
+        TRACK_RUN_IN_IPC_HANDLER(member_func); \
+        msg_class::Schema::Param p; \
+        if (msg_class::Read(&ipc_message__, &p)) { \
+          return ppapi::host::DispatchResourceCall( \
+              this, \
+              &_IpcMessageHandlerClass::member_func, \
+              context, p); \
+        } else { \
+          return PP_ERROR_FAILED; \
+        }  \
+      }  \
+      break;
+
+}  // namespace host
+}  // namespace ppapi