Convert the async device ID getter to a chrome resource host

ppapi/host/ppapi_host.cc

 // 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/ppapi_host.h"
 
 #include "base/logging.h"
 #include "ppapi/c/pp_errors.h"
 #include "ppapi/host/host_factory.h"
 #include "ppapi/host/host_message_context.h"
 #include "ppapi/host/instance_message_filter.h"
 #include "ppapi/host/resource_host.h"
 #include "ppapi/proxy/ppapi_messages.h"
 #include "ppapi/proxy/resource_message_params.h"
 #include "ppapi/shared_impl/host_resource.h"
 
 namespace ppapi {
 namespace host {
 
 namespace {
 
 // Put a cap on the maximum number of resources so we don't explode if the
 // renderer starts spamming us.
 const size_t kMaxResourcesPerPlugin = 1 << 14;
 
 }  // namespace
 
 PpapiHost::PpapiHost(IPC::Sender* sender,
-                     HostFactory* host_factory,
                      const PpapiPermissions& perms)
     : sender_(sender),
-      host_factory_(host_factory),
       permissions_(perms) {
 }
 
 PpapiHost::~PpapiHost() {
   // Delete these explicitly before destruction since then the host is still
   // technically alive in case one of the filters accesses us from the
   // destructor.
   instance_message_filters_.clear();
 }
 
@@ skipping 23 matching lines @@
   }
 
   return handled;
 }
 
 void PpapiHost::SendReply(const proxy::ResourceMessageReplyParams& params,
                           const IPC::Message& msg) {
   Send(new PpapiPluginMsg_ResourceReply(params, msg));
 }
 
+void PpapiHost::AddHostFactoryFilter(scoped_ptr<HostFactory> filter) {
+  host_factory_filters_.push_back(filter.release());
+}
 
 void PpapiHost::AddInstanceMessageFilter(
     scoped_ptr<InstanceMessageFilter> filter) {
   instance_message_filters_.push_back(filter.release());
 }
 
 void PpapiHost::OnHostMsgResourceCall(
     const proxy::ResourceMessageCallParams& params,
     const IPC::Message& nested_msg) {
   HostMessageContext context(params);
@@ skipping 28 matching lines @@
     SendReply(reply_params, context.reply_msg);
 }
 
 void PpapiHost::OnHostMsgResourceCreated(
     const proxy::ResourceMessageCallParams& params,
     PP_Instance instance,
     const IPC::Message& nested_msg) {
   if (resources_.size() >= kMaxResourcesPerPlugin)
     return;
 
-  scoped_ptr<ResourceHost> resource_host(
-      host_factory_->CreateResourceHost(this, params, instance, nested_msg));
+  // Run through all filters until one grabs this message.
+  scoped_ptr<ResourceHost> resource_host;
+  DCHECK(!host_factory_filters_.empty());  // Caller forgot to add a factory.
+  for (size_t i = 0; i < host_factory_filters_.size(); i++) {
+    resource_host = host_factory_filters_[i]->CreateResourceHost(
+        this, params, instance, nested_msg).Pass();
+    if (resource_host.get())
+      break;
+  }
   if (!resource_host.get()) {
     NOTREACHED();

[yzshen1, 2012/09/11 00:53:17]

According to the comment in resource_host.h
"Some (but not all) resources have a corresponding object in the host side"

So it seems okay to get NULL here.

[brettw, 2012/09/11 20:25:20]

If there isn't a corresponding host object, the proxy shouldn't be sending a
"created" message to the browser/renderer to create the host.

     return;
   }
 
   resources_[params.pp_resource()] =
       linked_ptr<ResourceHost>(resource_host.release());
 }
 
 void PpapiHost::OnHostMsgResourceDestroyed(PP_Resource resource) {
   ResourceMap::iterator found = resources_.find(resource);
   if (found == resources_.end()) {
     NOTREACHED();
     return;
   }
   resources_.erase(found);
 }
 
 ResourceHost* PpapiHost::GetResourceHost(PP_Resource resource) {
   ResourceMap::iterator found = resources_.find(resource);
   return found == resources_.end() ? NULL : found->second.get();
 }
 
 }  // namespace host
 }  // namespace ppapi