Defer synthetic gesture completions until events have been flushed

content/browser/renderer_host/input/input_router_impl.cc

Index: content/browser/renderer_host/input/input_router_impl.cc
diff --git a/content/browser/renderer_host/input/input_router_impl.cc b/content/browser/renderer_host/input/input_router_impl.cc
index 1028668e51100a582df1f4d54792935b6419897d..b6110d21648446332073c9b60b1a755c9b3a2a67 100644
--- a/content/browser/renderer_host/input/input_router_impl.cc
+++ b/content/browser/renderer_host/input/input_router_impl.cc
@@ -146,6 +146,7 @@ InputRouterImpl::InputRouterImpl(IPC::Sender* sender,
       touch_ack_timeout_supported_(false),
       current_view_flags_(0),
       current_ack_source_(ACK_SOURCE_NONE),
+      flush_requested_(false),
       gesture_event_queue_(new GestureEventQueue(this, this)) {
   DCHECK(sender);
   DCHECK(client);
@@ -159,7 +160,10 @@ InputRouterImpl::InputRouterImpl(IPC::Sender* sender,
 
 InputRouterImpl::~InputRouterImpl() {}
 
-void InputRouterImpl::Flush() {}
+void InputRouterImpl::Flush() {
+  flush_requested_ = true;
+  SignalFlushedIfNecessary();
+}
 
 bool InputRouterImpl::SendInput(scoped_ptr<IPC::Message> message) {
   DCHECK(IPC_MESSAGE_ID_CLASS(message->type()) == InputMsgStart);
@@ -623,6 +627,8 @@ void InputRouterImpl::ProcessInputEventAck(
   } else if (event_type != WebInputEvent::Undefined) {
     ack_handler_->OnUnexpectedEventAck(InputAckHandler::BAD_ACK_MESSAGE);
   }
+
+  SignalFlushedIfNecessary();
 }
 
 void InputRouterImpl::ProcessKeyboardAck(blink::WebInputEvent::Type type,
@@ -822,6 +828,27 @@ void InputRouterImpl::UpdateTouchAckTimeoutEnabled() {
                                            touch_ack_timeout_delay_);
 }
 
+void InputRouterImpl::SignalFlushedIfNecessary() {
+  if (!flush_requested_)
+    return;
+
+  if (HasPendingEvents())
+    return;
+
+  flush_requested_ = false;
+  client_->DidFlush();
+}
+
+bool InputRouterImpl::HasPendingEvents() const {
+  return !touch_event_queue_->empty() ||
+         gesture_event_queue_->HasQueuedGestureEvents() ||
+         !key_queue_.empty() ||
+         mouse_move_pending_ ||
+         mouse_wheel_pending_ ||
+         select_range_pending_ ||
+         move_caret_pending_;
+}
+
 bool InputRouterImpl::IsInOverscrollGesture() const {
   OverscrollController* controller = client_->GetOverscrollController();
   return controller && controller->overscroll_mode() != OVERSCROLL_NONE;