Always use an async TaskScheduler in TestBrowserThreadBundle.

chrome/browser/chromeos/policy/device_status_collector_browsertest.cc

Index: chrome/browser/chromeos/policy/device_status_collector_browsertest.cc
diff --git a/chrome/browser/chromeos/policy/device_status_collector_browsertest.cc b/chrome/browser/chromeos/policy/device_status_collector_browsertest.cc
index 2e99b27c7eedecbe09a39936dad5b8b0f3f19b9c..276c6365e2ed8467994c2a7543bbcc477ca2a091 100644
--- a/chrome/browser/chromeos/policy/device_status_collector_browsertest.cc
+++ b/chrome/browser/chromeos/policy/device_status_collector_browsertest.cc
@@ -154,7 +154,7 @@ class TestingDeviceStatusCollector : public policy::DeviceStatusCollector {
 
   void RefreshSampleResourceUsage() {
     SampleResourceUsage();
-    content::BrowserThread::GetBlockingPool()->FlushForTesting();
+    content::RunAllBlockingPoolTasksUntilIdle();
   }
 
  protected:
@@ -360,8 +360,7 @@ class DeviceStatusCollectorTest : public testing::Test {
     TestingBrowserProcess::GetGlobal()->SetLocalState(nullptr);
 
     // Finish pending tasks.
-    content::BrowserThread::GetBlockingPool()->FlushForTesting();
-    base::RunLoop().RunUntilIdle();

[fdoray, 2017/04/04 17:52:55]

When a synchronous TaskScheduler was used, base::RunLoop().RunUntilIdle()
indirectly flushed TaskScheduler. Now,
content::RunAllBlockingPoolTasksUntilIdle() is required to flush blocking pool +
task scheduler + main MessageLoop.

+    content::RunAllBlockingPoolTasksUntilIdle();
     storage::ExternalMountPoints::GetSystemInstance()->RevokeAllFileSystems();
     DiskMountManager::Shutdown();
   }
@@ -903,8 +902,7 @@ TEST_F(DeviceStatusCollectorTest, TestVolumeInfo) {
                          base::Bind(&GetEmptyCPUTempInfo),
                          base::Bind(&GetEmptyAndroidStatus));
   // Force finishing tasks posted by ctor of DeviceStatusCollector.
-  content::BrowserThread::GetBlockingPool()->FlushForTesting();
-  base::RunLoop().RunUntilIdle();
+  content::RunAllBlockingPoolTasksUntilIdle();
 
   GetStatus();
   EXPECT_EQ(expected_mount_points.size(),
@@ -957,8 +955,7 @@ TEST_F(DeviceStatusCollectorTest, TestCPUSamples) {
                          base::Bind(&GetEmptyCPUTempInfo),
                          base::Bind(&GetEmptyAndroidStatus));
   // Force finishing tasks posted by ctor of DeviceStatusCollector.
-  content::BrowserThread::GetBlockingPool()->FlushForTesting();
-  base::RunLoop().RunUntilIdle();
+  content::RunAllBlockingPoolTasksUntilIdle();
   GetStatus();
   ASSERT_EQ(1, device_status_.cpu_utilization_pct().size());
   EXPECT_EQ(100, device_status_.cpu_utilization_pct(0));
@@ -1009,8 +1006,7 @@ TEST_F(DeviceStatusCollectorTest, TestCPUTemp) {
                          base::Bind(&GetFakeCPUTempInfo, expected_temp_info),
                          base::Bind(&GetEmptyAndroidStatus));
   // Force finishing tasks posted by ctor of DeviceStatusCollector.
-  content::BrowserThread::GetBlockingPool()->FlushForTesting();
-  base::RunLoop().RunUntilIdle();
+  content::RunAllBlockingPoolTasksUntilIdle();
 
   GetStatus();
   EXPECT_EQ(expected_temp_info.size(),