[Media Router tests] Add minimal ScopedAllowIO for the tests to pass.

chrome/test/media_router/media_router_integration_browsertest.cc

 // Copyright 2015 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 "chrome/test/media_router/media_router_integration_browsertest.h"
 
 #include <memory>
 
 #include "base/bind.h"
 #include "base/files/file_util.h"
 #include "base/json/json_file_value_serializer.h"
 #include "base/json/json_reader.h"
 #include "base/json/json_writer.h"
 #include "base/path_service.h"
 #include "base/strings/stringprintf.h"
+#include "base/threading/thread_restrictions.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/browser_finder.h"
 #include "chrome/browser/ui/tabs/tab_strip_model.h"
 #include "chrome/browser/ui/views/frame/browser_view.h"
 #include "chrome/browser/ui/webui/media_router/media_router_dialog_controller_impl.h"
 #include "chrome/common/url_constants.h"
 #include "chrome/test/base/ui_test_utils.h"
 #include "content/public/browser/render_frame_host.h"
 #include "content/public/test/browser_test_utils.h"
@@ skipping 246 matching lines @@
 void MediaRouterIntegrationBrowserTest::CheckDialogRemainsOpen(
     WebContents* web_contents) {
   ASSERT_FALSE(ConditionalWait(
       base::TimeDelta::FromSeconds(5), base::TimeDelta::FromSeconds(1),
       base::Bind(&MediaRouterIntegrationBrowserTest::IsDialogClosed,
                  base::Unretained(this), web_contents)));
 }
 
 void MediaRouterIntegrationBrowserTest::SetTestData(
     base::FilePath::StringPieceType test_data_file) {
+  // crbug.com/724573
+  base::ThreadRestrictions::ScopedAllowIO allow_io;

[mark a. foltz, 2017/05/30 23:50:04]

I don't see anything in this stack frame that requires IO.
Did I miss something?

[imcheng, 2017/05/31 00:30:22]

JSONFileValueDeserializer::Deserialize requires it. I scoped allow_io to only
that call.

   base::FilePath full_path = GetResourceFile(test_data_file);
   JSONFileValueDeserializer deserializer(full_path);
   int error_code = 0;
   std::string error_message;
   std::unique_ptr<base::Value> value =
       deserializer.Deserialize(&error_code, &error_message);
   CHECK(value.get()) << "Deserialize failed: " << error_message;
   std::string test_data_str;
   ASSERT_TRUE(base::JSONWriter::Write(*value, &test_data_str));
   ExecuteScriptInBackgroundPageNoWait(
@@ skipping 13 matching lines @@
   test_navigation_observer_->Wait();
   test_navigation_observer_->StopWatchingNewWebContents();
   WebContents* dialog_contents = controller->GetMediaRouterDialog();
   CHECK(dialog_contents);
   WaitUntilDialogFullyLoaded(dialog_contents);
   return dialog_contents;
 }
 
 base::FilePath MediaRouterIntegrationBrowserTest::GetResourceFile(
     base::FilePath::StringPieceType relative_path) const {
+  // crbug.com/724573
+  base::ThreadRestrictions::ScopedAllowIO allow_io;

[mark a. foltz, 2017/05/30 23:50:03]

Can this be scoped to only include PathExists?

[imcheng, 2017/05/31 00:30:22]

Done.

   base::FilePath base_dir;
   // ASSERT_TRUE can only be used in void returning functions.
   // Use CHECK instead in non-void returning functions.
   CHECK(PathService::Get(base::DIR_MODULE, &base_dir));
   base::FilePath full_path =
       base_dir.Append(kResourcePath).Append(relative_path);
   CHECK(PathExists(full_path));
   return full_path;
 }
 
@@ skipping 334 matching lines @@
                        MANUAL_Basic) {
   RunBasicTest();
 }
 
 IN_PROC_BROWSER_TEST_F(MediaRouterIntegrationIncognitoBrowserTest,
                        MANUAL_ReconnectSession) {
   RunReconnectSessionTest();
 }
 
 }  // namespace media_router