Change ServiceManagerConnectionImpl to run service request handlers on the IO thread.

chrome/browser/chrome_content_browser_client.cc

Index: chrome/browser/chrome_content_browser_client.cc
diff --git a/chrome/browser/chrome_content_browser_client.cc b/chrome/browser/chrome_content_browser_client.cc
index 338d2e85ff4c27430a7f24d130f163bf2366ce06..add454a73af479000cb0732ffc762e8e6a25c5a3 100644
--- a/chrome/browser/chrome_content_browser_client.cc
+++ b/chrome/browser/chrome_content_browser_client.cc
@@ -3231,6 +3231,7 @@ void ChromeContentBrowserClient::RegisterInProcessServices(
     content::ServiceInfo info;
     info.factory = base::Bind(&ash_util::CreateEmbeddedAshService,
                               base::ThreadTaskRunnerHandle::Get());
+    info.task_runner = base::ThreadTaskRunnerHandle::Get();
     services->insert(std::make_pair(ash::mojom::kServiceName, info));
   }
 #endif  // OS_CHROMEOS