Add BeforeWait calls to to MessagePumpForIO:DoRunLoop

Bug: 1034046
Change-Id: Iaca83f31e2b91f928faa4454843710bcb419fba5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2095610
Auto-Submit: Oliver Li <olivierli@google.com>
Commit-Queue: Oliver Li <olivierli@google.com>
Commit-Queue: François Doray <fdoray@chromium.org>
Reviewed-by: François Doray <fdoray@chromium.org>
Cr-Commit-Position: refs/heads/master@{#748834}

base/message_loop/message_pump_win.cc

@@ -624,6 +624,7 @@ void MessagePumpForIO::DoRunLoop() {
     if (state_->should_quit)
       break;
 
+    state_->delegate->BeforeWait();
     more_work_is_plausible |= WaitForIOCompletion(0, nullptr);
     if (state_->should_quit)
       break;
@@ -638,6 +639,7 @@ void MessagePumpForIO::DoRunLoop() {
     if (more_work_is_plausible)
       continue;
 
+    state_->delegate->BeforeWait();
     WaitForWork(next_work_info);
   }
 }