Implement Main Thread RAF Aligned Input

content/common/input/web_input_event_queue.h

Index: content/common/input/web_input_event_queue.h
diff --git a/content/common/input/web_input_event_queue.h b/content/common/input/web_input_event_queue.h
index 5677c539d7ebd90737ff316b2b3926140bd75967..59a4d9a9c42241cf02b3f843c97e306fe197e900 100644
--- a/content/common/input/web_input_event_queue.h
+++ b/content/common/input/web_input_event_queue.h
@@ -36,6 +36,9 @@ class WebInputEventQueue {
     queue_.emplace_back(std::move(event));
   }
 
+  const std::unique_ptr<T>& front() const { return queue_.front(); }
+  const std::unique_ptr<T>& at(size_t pos) const { return queue_.at(pos); }
+
   std::unique_ptr<T> Pop() {
     std::unique_ptr<T> result;
     if (!queue_.empty()) {