Bug 1493275 - Annotate idle stacks in the chromium event loop on Windows. r=froydnj

Depends on D6533

Differential Revision: https://phabricator.services.mozilla.com/D6534

--HG--
extra : moz-landing-system : lando

ipc/chromium/src/base/message_pump_win.cc

@@ -12,6 +12,7 @@
 #include "base/histogram.h"
 #include "base/win_util.h"
 #include "WinUtils.h"
+#include "GeckoProfiler.h"
 
 using base::Time;
 
@@ -252,6 +253,8 @@ void MessagePumpForUI::InitMessageWnd() {
 }
 
 void MessagePumpForUI::WaitForWork() {
+  AUTO_PROFILER_LABEL("MessagePumpForUI::WaitForWork", IDLE);
+
   // Wait until a message is available, up to the time needed by the timer
   // manager to fire the next set of timers.
   int delay = GetCurrentDelay();