Hook up the PPB_Flash_Print interface to new host system.

ppapi/host/ppapi_host.h

Index: ppapi/host/ppapi_host.h
diff --git a/ppapi/host/ppapi_host.h b/ppapi/host/ppapi_host.h
index 7a20c1fe286dee65fba2cc0cb80a00a1a84269a4..306472447cd3d4a309b9851c5b6e7761b85d8929 100644
--- a/ppapi/host/ppapi_host.h
+++ b/ppapi/host/ppapi_host.h
@@ -9,6 +9,7 @@
 
 #include "base/compiler_specific.h"
 #include "base/memory/linked_ptr.h"
+#include "base/observer_list.h"
 #include "ipc/ipc_listener.h"
 #include "ipc/ipc_sender.h"
 #include "ppapi/c/pp_instance.h"
@@ -26,6 +27,7 @@ class ResourceMessageReplyParams;
 namespace host {
 
 class HostFactory;
+class InstanceMessageFilter;
 class ResourceHost;
 
 // The host provides routing and tracking for resource message calls that
@@ -33,8 +35,8 @@ class ResourceHost;
 // corresponding replies.
 class PPAPI_HOST_EXPORT PpapiHost : public IPC::Sender, public IPC::Listener {
  public:
-  // The sender is the channel to the plugin for outgoing messages. The factory
-  // will be used to receive resource creation messages from the plugin. Both
+  // The sender is the channel to the plugin for outgoing messages. The factory
+  // will be used to receive resource creation messages from the plugin. Both
   // pointers are owned by the caller and must outlive this class.
   PpapiHost(IPC::Sender* sender,
             HostFactory* host_factory,
@@ -54,6 +56,11 @@ class PPAPI_HOST_EXPORT PpapiHost : public IPC::Sender, public IPC::Listener {
                  const IPC::Message& msg);
 
  private:
+  friend class InstanceMessageFilter;
+
+  void AddInstanceMessageFilter(InstanceMessageFilter* filter);
+  void RemoveInstanceMessageFilter(InstanceMessageFilter* filter);
+
   // Message handlers.
   void OnHostMsgResourceCall(const proxy::ResourceMessageCallParams& params,
                              const IPC::Message& nested_msg);
@@ -73,6 +80,9 @@ class PPAPI_HOST_EXPORT PpapiHost : public IPC::Sender, public IPC::Listener {
 
   PpapiPermissions permissions_;
 
+  // Filters for instance messages. Non-owning pointers.
+  ObserverList<InstanceMessageFilter> instance_message_filters_;
+
   typedef std::map<PP_Resource, linked_ptr<ResourceHost> > ResourceMap;
   ResourceMap resources_;