Remove use of deprecated MessageLoop methods in chrome/.

chrome/browser/extensions/extension_install_prompt.cc

Index: chrome/browser/extensions/extension_install_prompt.cc
diff --git a/chrome/browser/extensions/extension_install_prompt.cc b/chrome/browser/extensions/extension_install_prompt.cc
index 1bc9fa1c809d8ae74390c88230ea9c6cf8fc63de..451abf1a9654c67b4737f44f5b92dfe1040a1d29 100644
--- a/chrome/browser/extensions/extension_install_prompt.cc
+++ b/chrome/browser/extensions/extension_install_prompt.cc
@@ -9,6 +9,7 @@
 #include "base/callback_helpers.h"
 #include "base/location.h"
 #include "base/memory/ptr_util.h"
+#include "base/single_thread_task_runner.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
@@ -154,7 +155,7 @@ bool AutoConfirmPrompt(ExtensionInstallPrompt::DoneCallback* callback) {
     // the real implementations it's highly likely the message loop will be
     // pumping a few times before the user clicks accept or cancel.
     case extensions::ScopedTestDialogAutoConfirm::ACCEPT:
-      base::MessageLoop::current()->PostTask(
+      base::ThreadTaskRunnerHandle::Get()->PostTask(
           FROM_HERE, base::Bind(base::ResetAndReturn(callback),
                                 ExtensionInstallPrompt::Result::ACCEPTED));
       return true;