Delay Input.dispatchKeyEvent response until after key event ack.

content/browser/renderer_host/render_widget_host_impl.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/renderer_host/render_widget_host_impl.h"
 
 #include <math.h>
 
 #include <set>
 #include <tuple>
@@ skipping 1936 matching lines @@
     ui::LatencyInfo* latency) {
   latency_tracker_.OnInputEvent(event, latency);
   for (auto& observer : input_event_observers_)
     observer.OnInputEvent(event);
 }
 
 void RenderWidgetHostImpl::OnKeyboardEventAck(
       const NativeWebKeyboardEventWithLatencyInfo& event,
       InputEventAckState ack_result) {
   latency_tracker_.OnInputEventAck(event.event, &event.latency, ack_result);
+  FOR_EACH_OBSERVER(InputEventObserver, input_event_observers_,
+                    OnInputEventAck(event.event, event.event.is_synthetic));
 
   const bool processed = (INPUT_EVENT_ACK_STATE_CONSUMED == ack_result);
 
   // We only send unprocessed key event upwards if we are not hidden,
   // because the user has moved away from us and no longer expect any effect
   // of this key event.
   if (delegate_ && !processed && !is_hidden() && !event.event.skip_in_browser) {
     delegate_->HandleKeyboardEvent(event.event);
 
     // WARNING: This RenderWidgetHostImpl can be deallocated at this point
     // (i.e.  in the case of Ctrl+W, where the call to
     // HandleKeyboardEvent destroys this RenderWidgetHostImpl).
   }
 }
 
 void RenderWidgetHostImpl::OnMouseEventAck(
     const MouseEventWithLatencyInfo& mouse_event,
     InputEventAckState ack_result) {
   latency_tracker_.OnInputEventAck(mouse_event.event, &mouse_event.latency,
                                    ack_result);
+  // TOOD(samuong): keep track of synthetic mouse events
+  FOR_EACH_OBSERVER(InputEventObserver, input_event_observers_,
+                    OnInputEventAck(mouse_event.event, true));

[samuong, 2016/10/20 23:36:18]

Right now I'm setting is_synthetic to true for *all* mouse events. Unlike key
events, there is no content-level NativeWebMouseEvent, only the blink-level
WebMouseEvent. So there's a few options here:

1. add blink::WebMouseEvent::is_synthetic
2. create content::NativeWebMouseEvent and add an is_synthetic property
3. forget about this, since we don't really support the use case where we mix
synthetic and user inputs anyway

Can you let me know what you think here?

 }
 
 void RenderWidgetHostImpl::OnWheelEventAck(
     const MouseWheelEventWithLatencyInfo& wheel_event,
     InputEventAckState ack_result) {
   latency_tracker_.OnInputEventAck(wheel_event.event, &wheel_event.latency,
                                    ack_result);
+  FOR_EACH_OBSERVER(InputEventObserver, input_event_observers_,
+                    OnInputEventAck(wheel_event.event, false));
 
   if (!is_hidden() && view_) {
     if (ack_result != INPUT_EVENT_ACK_STATE_CONSUMED &&
         delegate_ && delegate_->HandleWheelEvent(wheel_event.event)) {
       ack_result = INPUT_EVENT_ACK_STATE_CONSUMED;
     }
     view_->WheelEventAck(wheel_event.event, ack_result);
   }
 }
 
 void RenderWidgetHostImpl::OnGestureEventAck(
     const GestureEventWithLatencyInfo& event,
     InputEventAckState ack_result) {
   latency_tracker_.OnInputEventAck(event.event, &event.latency, ack_result);
+  FOR_EACH_OBSERVER(InputEventObserver, input_event_observers_,
+                    OnInputEventAck(event.event, false));
 
   if (view_)
     view_->GestureEventAck(event.event, ack_result);
 }
 
 void RenderWidgetHostImpl::OnTouchEventAck(
     const TouchEventWithLatencyInfo& event,
     InputEventAckState ack_result) {
   latency_tracker_.OnInputEventAck(event.event, &event.latency, ack_result);
+  FOR_EACH_OBSERVER(InputEventObserver, input_event_observers_,
+                    OnInputEventAck(event.event, false));
 
   if (touch_emulator_ &&
       touch_emulator_->HandleTouchEventAck(event.event, ack_result)) {
     return;
   }
 
   if (view_)
     view_->ProcessAckedTouchEvent(event, ack_result);
 }
 
@@ skipping 205 matching lines @@
   return delegate_ ? delegate_->GetRootBrowserAccessibilityManager() : NULL;
 }
 
 BrowserAccessibilityManager*
     RenderWidgetHostImpl::GetOrCreateRootBrowserAccessibilityManager() {
   return delegate_ ?
       delegate_->GetOrCreateRootBrowserAccessibilityManager() : NULL;
 }
 
 }  // namespace content