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

ppapi/proxy/printing_resource_unittest.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 <cstring>
 
 #include "base/message_loop/message_loop.h"
 #include "ppapi/c/dev/ppb_printing_dev.h"
 #include "ppapi/c/pp_errors.h"
 #include "ppapi/proxy/locking_resource_releaser.h"
+#include "ppapi/proxy/plugin_message_filter.h"
 #include "ppapi/proxy/ppapi_messages.h"
 #include "ppapi/proxy/ppapi_proxy_test.h"
 #include "ppapi/proxy/printing_resource.h"
 #include "ppapi/thunk/thunk.h"
 
 namespace ppapi {
 namespace proxy {
 
 namespace {
 
@@ skipping 48 matching lines @@
   PP_PrintSettings_Dev reply_settings = {
     { { 0, 0 }, { 500, 515 } },
     { { 25, 35 }, { 300, 720 } },
     { 600, 700 },
     200,
     PP_PRINTORIENTATION_NORMAL,
     PP_PRINTSCALINGOPTION_NONE,
     PP_FALSE,
     PP_PRINTOUTPUTFORMAT_PDF
   };
-  ASSERT_TRUE(plugin_dispatcher()->OnMessageReceived(
-      PpapiPluginMsg_ResourceReply(reply_params,
-          PpapiPluginMsg_Printing_GetDefaultPrintSettingsReply(
-              reply_settings))));
+  PluginMessageFilter::DispatchResourceReplyForTest(
+      reply_params,
+      PpapiPluginMsg_Printing_GetDefaultPrintSettingsReply(
+          reply_settings));
 
   EXPECT_TRUE(PP_RectEqual(reply_settings.printable_area,
                            output_settings.printable_area));
   EXPECT_TRUE(PP_RectEqual(reply_settings.content_area,
                            output_settings.content_area));
   EXPECT_TRUE(PP_SizeEqual(reply_settings.paper_size,
                            output_settings.paper_size));
   EXPECT_EQ(reply_settings.dpi, output_settings.dpi);
   EXPECT_EQ(reply_settings.orientation, output_settings.orientation);
   EXPECT_EQ(reply_settings.print_scaling_option,
             output_settings.print_scaling_option);
   EXPECT_EQ(reply_settings.grayscale, output_settings.grayscale);
   EXPECT_EQ(reply_settings.format, output_settings.format);
 
   EXPECT_EQ(g_callback_result, PP_OK);
   EXPECT_EQ(g_callback_called, true);
 }
 
 }  // namespace proxy
 }  // namespace ppapi