[PPAPI] It is now possible to pass filesystems from JavaScript to NaCl modules.

ppapi/proxy/plugin_var_tracker.cc

Index: ppapi/proxy/plugin_var_tracker.cc
diff --git a/ppapi/proxy/plugin_var_tracker.cc b/ppapi/proxy/plugin_var_tracker.cc
index 0788b99923d44b5f4392d69374dbdb6e202c1c2e..a9cbd9c7a62bd2e6fdefc9b4b7f4d2c552ed8ba6 100644
--- a/ppapi/proxy/plugin_var_tracker.cc
+++ b/ppapi/proxy/plugin_var_tracker.cc
@@ -6,10 +6,13 @@
 
 #include "base/memory/ref_counted.h"
 #include "base/memory/singleton.h"
+#include "ipc/ipc_message.h"
 #include "ppapi/c/dev/ppp_class_deprecated.h"
 #include "ppapi/c/ppb_var.h"
+#include "ppapi/proxy/file_system_resource.h"
 #include "ppapi/proxy/plugin_array_buffer_var.h"
 #include "ppapi/proxy/plugin_dispatcher.h"
+#include "ppapi/proxy/plugin_globals.h"
 #include "ppapi/proxy/plugin_resource_var.h"
 #include "ppapi/proxy/ppapi_messages.h"
 #include "ppapi/proxy/proxy_object_var.h"
@@ -22,6 +25,16 @@
 namespace ppapi {
 namespace proxy {
 
+namespace {
+
+Connection GetConnectionForInstance(PP_Instance instance) {
+  PluginDispatcher* dispatcher = PluginDispatcher::GetForInstance(instance);
+  DCHECK(dispatcher);
+  return Connection(PluginGlobals::Get()->GetBrowserSender(), dispatcher);
+}
+
+}  // namespace
+
 PluginVarTracker::HostVar::HostVar(PluginDispatcher* d, int32 i)
     : dispatcher(d),
       host_object_id(i) {
@@ -154,6 +167,41 @@ void PluginVarTracker::ReleaseHostObject(PluginDispatcher* dispatcher,
   ReleaseVar(found->second);
 }
 
+PP_Var PluginVarTracker::MakeResourcePPVarFromMessage(
+    PP_Instance instance,
+    const IPC::Message& creation_message,
+    int pending_renderer_id,
+    int pending_browser_id) {
+  DCHECK(pending_renderer_id);
+  DCHECK(pending_browser_id);
+  switch (creation_message.type()) {
+    case PpapiPluginMsg_FileSystem_CreateFromPendingHost::ID: {
+      PP_FileSystemType file_system_type;
+      if (!UnpackMessage<PpapiPluginMsg_FileSystem_CreateFromPendingHost>(
+               creation_message, &file_system_type)) {
+        NOTREACHED() << "Invalid message of type "
+                        "PpapiPluginMsg_FileSystem_CreateFromPendingHost";
+        return PP_MakeNull();
+      }
+      // Create a plugin-side resource and attach it to the host resource.
+      // Note: This only makes sense when the plugin is out of process (which
+      // should always be true when passing resource vars).
+      PP_Resource pp_resource =
+          (new FileSystemResource(GetConnectionForInstance(instance),
+                                  instance,
+                                  pending_renderer_id,
+                                  pending_browser_id,
+                                  file_system_type))->GetReference();
+      return MakeResourcePPVar(pp_resource);
+    }
+    default: {
+      NOTREACHED() << "Creation message has unexpected type "
+                   << creation_message.type();
+      return PP_MakeNull();
+    }
+  }
+}
+
 ResourceVar* PluginVarTracker::MakeResourceVar(PP_Resource pp_resource) {
   // The resource 0 returns a null resource var.
   if (!pp_resource)