Notify Blink about start of gesture scroll through a queued event.

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 410f686d6b00f4ab130d499ddb35ce02ad5191c8..56398fcc5a59d11f71c6616bada22378671b5195 100644
--- a/content/browser/renderer_host/input/input_router_impl.cc
+++ b/content/browser/renderer_host/input/input_router_impl.cc
@@ -9,6 +9,8 @@
 
 #include "base/auto_reset.h"
 #include "base/command_line.h"
+#include "base/debug/stack_trace.h"
+#include "base/logging.h"
 #include "base/metrics/histogram.h"
 #include "base/strings/string_number_conversions.h"
 #include "content/browser/renderer_host/input/gesture_event_queue.h"
@@ -152,20 +154,32 @@ void InputRouterImpl::SendGestureEvent(
   input_stream_validator_.Validate(original_gesture_event.event);
 
   GestureEventWithLatencyInfo gesture_event(original_gesture_event);
+  LOG(ERROR) << "======= mDebug " << __FUNCTION__ << " t="
+             << WebInputEventTraits::GetName(gesture_event.event.type);
 
   if (touch_action_filter_.FilterGestureEvent(&gesture_event.event))
     return;
 
+  //LOG(ERROR) << "======= mDebug " << __FUNCTION__ << " not filtered";
+
   wheel_event_queue_.OnGestureScrollEvent(gesture_event);
 
-  if (gesture_event.event.sourceDevice == blink::WebGestureDeviceTouchscreen)
+  if (gesture_event.event.sourceDevice == blink::WebGestureDeviceTouchscreen) {
+    if (gesture_event.event.type == blink::WebInputEvent::GestureScrollBegin) {
+      touch_event_queue_.PrependTouchScrollNotification();
+      //GestureEventWithLatencyInfo dummy_gesture_event;
+      //gesture_event_queue_.QueueEvent(dummy_gesture_event);
+    }
     touch_event_queue_.OnGestureScrollEvent(gesture_event);
+  }
 
   gesture_event_queue_.QueueEvent(gesture_event);
 }
 
 void InputRouterImpl::SendTouchEvent(
     const TouchEventWithLatencyInfo& touch_event) {
+  LOG(ERROR) << "======= mDebug " << __FUNCTION__
+             << " t=" << WebInputEventTraits::GetName(touch_event.event.type);
   input_stream_validator_.Validate(touch_event.event);
   touch_event_queue_.QueueEvent(touch_event);
 }
@@ -285,6 +299,7 @@ void InputRouterImpl::OnFilteringTouchEvent(
 void InputRouterImpl::OnGestureEventAck(
     const GestureEventWithLatencyInfo& event,
     InputEventAckState ack_result) {
+  // Does these lines define touchmove vs gsb queuing order?
   touch_event_queue_.OnGestureEventAck(event, ack_result);
   ack_handler_->OnGestureEventAck(event, ack_result);
 }
@@ -359,6 +374,9 @@ void InputRouterImpl::FilterAndSendWebInputEvent(
 
 void InputRouterImpl::OfferToHandlers(const WebInputEvent& input_event,
                                       const ui::LatencyInfo& latency_info) {
+  LOG(ERROR) << "======= mDebug " << __FUNCTION__
+             << " t=" << WebInputEventTraits::GetName(input_event.type);
+
   output_stream_validator_.Validate(input_event);
 
   if (OfferToClient(input_event, latency_info))