Tweaks to new BrowserThreadImpl/BrowserMainLoop logic.

content/browser/browser_main_loop.cc

Index: content/browser/browser_main_loop.cc
diff --git a/content/browser/browser_main_loop.cc b/content/browser/browser_main_loop.cc
index d57ddbe3c0b3a162a1ae1130efdd97c67715010a..916302e9ab085ab1c95dbd45a1e7b13ea19e82d3 100644
--- a/content/browser/browser_main_loop.cc
+++ b/content/browser/browser_main_loop.cc
@@ -1053,6 +1053,7 @@ int BrowserMainLoop::CreateThreads() {
         // redirecting the FILE thread on Windows. http://crbug.com/662122
         thread_to_start = &file_thread_;
         options = ui_message_loop_options;
+        options.timer_slack = base::TIMER_SLACK_MAXIMUM;

[gab, 2017/01/10 15:48:28]

Forgot to add this to the OS_WIN only section to match the other platforms'
non-redirection case as before.

 #else
         if (redirect_nonUInonIO_browser_threads) {
           non_ui_non_io_task_runner_traits