Send input message acks for swapped out renderers.

content/renderer/render_view_impl.h

Index: content/renderer/render_view_impl.h
diff --git a/content/renderer/render_view_impl.h b/content/renderer/render_view_impl.h
index ee2e21e3a83ad9429a9d891c78adca0ebe79e373..7ff1af95c6d4a5b4fc565512bc6bf4d8455b9e09 100644
--- a/content/renderer/render_view_impl.h
+++ b/content/renderer/render_view_impl.h
@@ -695,6 +695,11 @@ class CONTENT_EXPORT RenderViewImpl
 
   void UpdateWebViewWithDeviceScaleFactor();
 
+  // Send the appropriate ack to be able discard this input event message.
+  void OnDiscardInputEvent(const blink::WebInputEvent* input_event,
+                           const ui::LatencyInfo& latency_info,
+                           InputEventDispatchType dispatch_type);
+
   // ---------------------------------------------------------------------------
   // ADDING NEW FUNCTIONS? Please keep private functions alphabetized and put
   // it in the same order in the .cc file as it was in the header.