Delay Input.dispatchKeyEvent response until after key event ack.

content/browser/devtools/protocol/input_handler.cc

Index: content/browser/devtools/protocol/input_handler.cc
diff --git a/content/browser/devtools/protocol/input_handler.cc b/content/browser/devtools/protocol/input_handler.cc
index 04be3a8e487ec7ff0f44b35f1fbaf1e5c8fc5e5e..d679d9dae95124a15a30c87c44a6691016d2bd61 100644
--- a/content/browser/devtools/protocol/input_handler.cc
+++ b/content/browser/devtools/protocol/input_handler.cc
@@ -137,6 +137,15 @@ InputHandler::InputHandler()
 InputHandler::~InputHandler() {
 }
 
+void InputHandler::OnInputEventAck(const blink::WebInputEvent& event,
+                                   bool was_synthetic) {

[tdresser, 2016/10/12 19:49:36]

We appear to switch between is_synthetic and was_synthetic.

Let's use is_synthetic throughout?

[samuong, 2016/10/13 22:59:10]

Done.

+  if (blink::WebInputEvent::isKeyboardEventType(event.type) && was_synthetic) {
+    DCHECK(!pending_key_event_ids_.empty());

[tdresser, 2016/10/12 19:49:36]

A compromised renderer could send bogus acks, and they shouldn't make us crash.
We should probably have an early return here if there are no pending key event
ids.

[samuong, 2016/10/13 22:59:10]

Done. That's a good point, I've added this to the if condition so we won't do
anything if we receive an ack while the queue is empty.

+    SendDispatchKeyEventResponse(pending_key_event_ids_.front());
+    pending_key_event_ids_.pop();
+  }
+}
+
 void InputHandler::SetRenderWidgetHost(RenderWidgetHostImpl* host) {
   host_ = host;
 }
@@ -152,6 +161,7 @@ void InputHandler::OnSwapCompositorFrame(
 }
 
 Response InputHandler::DispatchKeyEvent(
+    DevToolsCommandId command_id,
     const std::string& type,
     const int* modifiers,
     const double* timestamp,
@@ -167,6 +177,7 @@ Response InputHandler::DispatchKeyEvent(
     const bool* is_system_key) {
   NativeWebKeyboardEvent event;
   event.skip_in_browser = true;
+  event.is_synthetic = true;
 
   if (type == dispatch_key_event::kTypeKeyDown) {
     event.type = blink::WebInputEvent::KeyDown;
@@ -212,6 +223,7 @@ Response InputHandler::DispatchKeyEvent(
   if (!host_)
     return Response::ServerError("Could not connect to view");
 
+  pending_key_event_ids_.push(command_id);
   host_->Focus();
   host_->ForwardKeyboardEvent(event);
   return Response::OK();
@@ -471,6 +483,11 @@ Response InputHandler::SynthesizeTapGesture(
   return Response::OK();
 }
 
+void InputHandler::SendDispatchKeyEventResponse(DevToolsCommandId command_id) {
+  client_->SendDispatchKeyEventResponse(
+      command_id, DispatchKeyEventResponse::Create());
+}
+
 void InputHandler::SendSynthesizePinchGestureResponse(
     DevToolsCommandId command_id,
     SyntheticGesture::Result result) {