Don't send touch move to renderer while scrolling

content/browser/renderer_host/input/immediate_input_router.cc

 // Copyright 2013 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/input/immediate_input_router.h"
 
 #include "base/command_line.h"
 #include "base/metrics/histogram.h"
 #include "content/browser/renderer_host/input/gesture_event_filter.h"
 #include "content/browser/renderer_host/input/input_router_client.h"
@@ skipping 67 matching lines @@
     : process_(process),
       client_(client),
       routing_id_(routing_id),
       select_range_pending_(false),
       move_caret_pending_(false),
       mouse_move_pending_(false),
       mouse_wheel_pending_(false),
       has_touch_handler_(false),
       touch_event_queue_(new TouchEventQueue(this)),
       gesture_event_filter_(new GestureEventFilter(this)) {
+  enable_no_touch_to_renderer_while_scrolling_ =
+      CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
+          switches::kNoTouchToRendererWhileScrolling) == "1";
   DCHECK(process);
   DCHECK(client);
 }
 
 ImmediateInputRouter::~ImmediateInputRouter() {
 }
 
 bool ImmediateInputRouter::SendInput(IPC::Message* message) {
   DCHECK(IPC_MESSAGE_ID_CLASS(message->type()) == InputMsgStart);
   scoped_ptr<IPC::Message> scoped_message(message);
@@ skipping 94 matching lines @@
   HISTOGRAM_COUNTS_100("Renderer.KeyboardQueueSize", key_queue_.size());
 
   gesture_event_filter_->FlingHasBeenHalted();
 
   // Only forward the non-native portions of our event.
   FilterAndSendWebInputEvent(key_event, latency_info, is_shortcut);
 }
 
 void ImmediateInputRouter::SendGestureEvent(
     const GestureEventWithLatencyInfo& gesture_event) {
+  HandleGestureScroll(gesture_event);
   if (!client_->OnSendGestureEvent(gesture_event))
     return;
   FilterAndSendWebInputEvent(gesture_event.event, gesture_event.latency, false);
 }
 
 void ImmediateInputRouter::SendTouchEvent(
     const TouchEventWithLatencyInfo& touch_event) {
   // Always queue TouchEvents, even if the client request they be dropped.
   client_->OnSendTouchEvent(touch_event);
   touch_event_queue_->QueueEvent(touch_event);
@@ skipping 33 matching lines @@
 
 void ImmediateInputRouter::SendTouchEventImmediately(
     const TouchEventWithLatencyInfo& touch_event) {
   if (!client_->OnSendTouchEventImmediately(touch_event))
     return;
   FilterAndSendWebInputEvent(touch_event.event, touch_event.latency, false);
 }
 
 void ImmediateInputRouter::SendGestureEventImmediately(
     const GestureEventWithLatencyInfo& gesture_event) {
+  HandleGestureScroll(gesture_event);
   if (!client_->OnSendGestureEventImmediately(gesture_event))
     return;
   FilterAndSendWebInputEvent(gesture_event.event, gesture_event.latency, false);
 }
 
 const NativeWebKeyboardEvent*
     ImmediateInputRouter::GetLastKeyboardEvent() const {
   if (key_queue_.empty())
     return NULL;
   return &key_queue_.front();
@@ skipping 277 matching lines @@
   client_->OnGestureEventAck(
       gesture_event_filter_->GetGestureEventAwaitingAck(), ack_result);
   gesture_event_filter_->ProcessGestureAck(processed, type);
 }
 
 void ImmediateInputRouter::ProcessTouchAck(InputEventAckState ack_result) {
   // |touch_event_queue_| will forward to OnTouchEventAck when appropriate.
   touch_event_queue_->ProcessTouchAck(ack_result);
 }
 
+void ImmediateInputRouter::HandleGestureScroll(
+    const GestureEventWithLatencyInfo& gesture_event) {
+  if (!enable_no_touch_to_renderer_while_scrolling_)
+    return;
+
+  // Once scrolling is started stop forwarding touch move events to renderer.
+  if (gesture_event.event.type == WebInputEvent::GestureScrollUpdate)

[sadrul, 2013/08/13 19:40:04]

Please consider using GestureScrollBegin instead of Update.

[Yufeng Shen (Slow to review), 2013/08/13 20:17:27]

Done.

+    touch_event_queue_->set_no_touch_move_to_renderer(true);
+
+  if (gesture_event.event.type == WebInputEvent::GestureScrollEnd ||
+      gesture_event.event.type == WebInputEvent::GestureFlingStart) {
+    touch_event_queue_->set_no_touch_move_to_renderer(false);
+  }
+}
+
 }  // namespace content