Hook up the PPB_Flash_Print interface to new host system.

ppapi/host/instance_message_filter.cc

Index: ppapi/host/instance_message_filter.cc
diff --git a/ppapi/host/instance_message_filter.cc b/ppapi/host/instance_message_filter.cc
new file mode 100644
index 0000000000000000000000000000000000000000..b7117488863bb57ebc6f795d3efc32a6be37ec58
--- /dev/null
+++ b/ppapi/host/instance_message_filter.cc
@@ -0,0 +1,30 @@
+// 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 "ppapi/host/instance_message_filter.h"
+
+#include "ppapi/host/ppapi_host.h"
+
+namespace ppapi {
+namespace host {
+
+InstanceMessageFilter::InstanceMessageFilter(PpapiHost* host)
+    : host_(host) {
+  host_->AddInstanceMessageFilter(this);
+}
+
+InstanceMessageFilter::~InstanceMessageFilter() {
+  if (host_)
+    host_->RemoveInstanceMessageFilter(this);
+}
+
+void InstanceMessageFilter::CallPpapiHostDestroyed() {
+  host_->RemoveInstanceMessageFilter(this);
+  PpapiHost* host = host_;
+  host_ = NULL;
+  PpapiHostDestroyed(host);

[dmichael (off chromium), 2012/07/25 16:57:27]

If the host is in the process of being destroyed, maybe passing host is
potentially a little dangerous. I would take that param out, unless you're sure
you need it.

Should we consider having |delete this| here at the end, so we can't forget? Or
are you anticipating some of these filters outliving the host? Alternatively,
the PpapiHostDestroyed virtual function could be pure-virtual, just to force
derived classes to think about it.

[brettw, 2012/07/26 16:18:12]

This seems reasonable. I'm not actually sure how this will end up being used.

+}
+
+}  // namespace host
+}  // namespace ppapi