Support using TrackedCallbacks as hints to determine the handling thread of resource reply messages

ppapi/proxy/plugin_message_filter.h

Index: ppapi/proxy/plugin_message_filter.h
diff --git a/ppapi/proxy/plugin_message_filter.h b/ppapi/proxy/plugin_message_filter.h
index 5701a96a09acc52e40d99f8bd4645a05ea8956d2..a16b53862c3e5c92992238b42481cc54d269be63 100644
--- a/ppapi/proxy/plugin_message_filter.h
+++ b/ppapi/proxy/plugin_message_filter.h
@@ -8,26 +8,37 @@
 #include <set>
 
 #include "base/compiler_specific.h"
+#include "base/memory/ref_counted.h"
 #include "ipc/ipc_channel_proxy.h"
 #include "ipc/ipc_sender.h"
 #include "ppapi/c/pp_instance.h"
+#include "ppapi/proxy/ppapi_proxy_export.h"
 
 namespace ppapi {
 namespace proxy {
 
+class ResourceMessageReplyParams;
+class ResourceReplyThreadRegistrar;
+
 // Listens for messages on the I/O thread of the plugin and handles some of
 // them to avoid needing to block on the plugin.
 //
 // There is one instance of this class for each renderer channel (same as for
 // the PluginDispatchers).
-class PluginMessageFilter : public IPC::ChannelProxy::MessageFilter,
-                            public IPC::Sender {
+class PPAPI_PROXY_EXPORT PluginMessageFilter
+    : public IPC::ChannelProxy::MessageFilter,
+      public IPC::Sender {
  public:
-  // The input is a pointer to a set that will be used to uniquify PP_Instances
-  // across all renderer channels. The same pointer should be passed to each
-  // MessageFilter to ensure uniqueness, and the value should outlive this
-  // class.
-  PluginMessageFilter(std::set<PP_Instance>* seen_instance_ids);
+  // |seen_instance_ids| is a pointer to a set that will be used to uniquify
+  // PP_Instances across all renderer channels. The same pointer should be
+  // passed to each MessageFilter to ensure uniqueness, and the value should
+  // outlive this class. It could be NULL if this filter is for a browser
+  // channel.
+  // |thread_registrar| is used to look up handling threads for resource
+  // reply messages. It shouldn't be NULL.
+  PluginMessageFilter(
+      std::set<PP_Instance>* seen_instance_ids,
+      scoped_refptr<ResourceReplyThreadRegistrar> thread_registrar);
   virtual ~PluginMessageFilter();
 
   // MessageFilter implementation.
@@ -38,14 +49,30 @@ class PluginMessageFilter : public IPC::ChannelProxy::MessageFilter,
   // IPC::Sender implementation.
   virtual bool Send(IPC::Message* msg) OVERRIDE;
 
+  // Simulates an incoming resource reply that is handled on the calling thread.
+  // For testing only.
+  static void DispatchResourceReplyForTest(
+      const ResourceMessageReplyParams& reply_params,
+      const IPC::Message& nested_msg);
+
  private:
   void OnMsgReserveInstanceId(PP_Instance instance, bool* usable);
+  void OnMsgResourceReply(const ResourceMessageReplyParams& reply_params,
+                          const IPC::Message& nested_msg);
+
+  // Dispatches the given resource reply to the appropriate resource in the
+  // plugin process.
+  static void DispatchResourceReply(
+      const ResourceMessageReplyParams& reply_params,
+      const IPC::Message& nested_msg);
 
   // All instance IDs every queried by any renderer on this plugin. This is
   // used to make sure that new instance IDs are unique. This is a non-owning
   // pointer, it will be managed by the later that creates this class.
   std::set<PP_Instance>* seen_instance_ids_;
 
+  scoped_refptr<ResourceReplyThreadRegistrar> resource_reply_thread_registrar_;
+
   // The IPC channel to the renderer. May be NULL if we're not currently
   // attached as a filter.
   IPC::Channel* channel_;