MD Settings: fix metrics reporting unittests on official testers -- take 2

chrome/browser/ui/webui/settings/metrics_reporting_handler_unittest.cc

 // Copyright 2016 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.
 
 #if defined(GOOGLE_CHROME_BUILD) && !defined(OS_CHROMEOS)
 
 #include "chrome/browser/ui/webui/settings/metrics_reporting_handler.h"
 
 #include "base/memory/ptr_util.h"
 #include "base/values.h"
@@ skipping 43 matching lines @@
     args.Append(base::WrapUnique(new base::FundamentalValue(1)));
     handler()->HandleGetMetricsReporting(&args);
 
     EXPECT_TRUE(handler()->IsJavascriptAllowed());
     EXPECT_EQ(1u, test_web_ui()->call_data().size());
 
     test_web_ui()->ClearTrackedCalls();
   }
 
   void TearDown() override {
+    // For crbug.com/637068 which only run on official bots with no try jobs.

[dschuyler, 2016/08/24 22:14:59]

I suggest ignoring this optional nit:
but just to be thorough s/run/runs/

+    base::RunLoop().RunUntilIdle();
     handler_.reset();
+    base::RunLoop().RunUntilIdle();
+    local_state_.reset();
+    base::RunLoop().RunUntilIdle();
   }
 
   PrefService* local_state() { return local_state_->Get(); }
   TestingMetricsReportingHandler* handler() { return handler_.get(); }
   content::TestWebUI* test_web_ui() { return &test_web_ui_; }
   policy::PolicyMap* map() { return &map_; }
   policy::MockConfigurationPolicyProvider* provider() { return &provider_; }
 
  private:
   content::TestBrowserThreadBundle thread_bundle_;
@@ skipping 43 matching lines @@
              policy::POLICY_SOURCE_CLOUD,
              base::WrapUnique(new base::FundamentalValue(false)),
              nullptr);
   provider()->UpdateChromePolicy(*map());
   EXPECT_TRUE(test_web_ui()->call_data().empty());
 }
 
 }  // namespace settings
 
 #endif  // defined(GOOGLE_CHROME_BUILD) && !defined(OS_CHROMEOS)