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

ppapi/proxy/raw_var_data.cc

Index: ppapi/proxy/raw_var_data.cc
diff --git a/ppapi/proxy/raw_var_data.cc b/ppapi/proxy/raw_var_data.cc
index 91bcfbfd1f0b0448126f2da92cc6081076cd1f14..d7b63693021adfbcd946971653fb992467a4ea35 100644
--- a/ppapi/proxy/raw_var_data.cc
+++ b/ppapi/proxy/raw_var_data.cc
@@ -9,7 +9,12 @@
 #include "base/containers/hash_tables.h"
 #include "base/stl_util.h"
 #include "ipc/ipc_message.h"
+#include "ppapi/proxy/file_system_resource.h"
+#include "ppapi/proxy/plugin_dispatcher.h"
+#include "ppapi/proxy/plugin_globals.h"
+#include "ppapi/proxy/ppapi_messages.h"
 #include "ppapi/proxy/ppapi_param_traits.h"
+#include "ppapi/proxy/resource_creation_proxy.h"
 #include "ppapi/shared_impl/array_var.h"
 #include "ppapi/shared_impl/dictionary_var.h"
 #include "ppapi/shared_impl/ppapi_globals.h"
@@ -64,6 +69,14 @@ bool CanHaveChildren(PP_Var var) {
   return var.type == PP_VARTYPE_ARRAY || var.type == PP_VARTYPE_DICTIONARY;
 }
 
+// Should only be called when the Pepper plugin is out of process.
+Connection GetConnectionForInstance(PP_Instance instance) {
+  PluginDispatcher* dispatcher = PluginDispatcher::GetForInstance(instance);
+  // GetForInstance returns NULL in the in-process case.
+  DCHECK(dispatcher);
+  return Connection(PluginGlobals::Get()->GetBrowserSender(), dispatcher);
+}
+
 }  // namespace
 
 // RawVarDataGraph ------------------------------------------------------------
@@ -695,12 +708,40 @@ bool ResourceRawVarData::Init(const PP_Var& var, PP_Instance /*instance*/) {
 }
 
 PP_Var ResourceRawVarData::CreatePPVar(PP_Instance instance) {
-  // If pp_resource_ is NULL, it could be because we are on the plugin side and
-  // there is a pending resource host on the renderer.
-  // TODO(mgiuca): Create a plugin-side resource in this case.
-  // Currently, this should never occur. This will be needed when passing a
-  // resource from the renderer to the plugin (http://crbug.com/177017).
-  DCHECK(pp_resource_);
+  // If we are on the plugin side, and the var is a pending resource host,
+  // create a plugin-side resource. A var is a pending resource host if it has a
+  // pp_resource of 0, and a non-null creation message.
+  if (PpapiGlobals::Get()->IsPluginGlobals() && !pp_resource_ &&
+      creation_message_) {
+    DCHECK(pending_renderer_host_id_);
+    DCHECK(pending_browser_host_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_ =
+            (new FileSystemResource(GetConnectionForInstance(instance),
+                                    instance,
+                                    pending_renderer_host_id_,
+                                    pending_browser_host_id_,
+                                    file_system_type))->GetReference();
+        break;
+      }
+      default: {
+        NOTREACHED() << "Creation message has unexpected type "
+                     << creation_message_->type();
+        return PP_MakeNull();
+      }
+    }
+  }
 
   return PpapiGlobals::Get()->GetVarTracker()->MakeResourcePPVar(pp_resource_);
 }