Disable touch ack timeout if MT responsiveness scroll intervention on.

content/browser/renderer_host/input/input_router_config_helper.cc

 // Copyright 2014 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/input_router_config_helper.h"
 
 #include "base/command_line.h"
+#include "base/feature_list.h"
 #include "build/build_config.h"
+#include "content/public/common/content_features.h"
 #include "content/public/common/content_switches.h"
 #include "ui/events/gesture_detection/gesture_configuration.h"
 #include "ui/events/gesture_detection/gesture_detector.h"
 
 namespace content {
 namespace {
 
 // Default time allowance for the touch ack delay before the touch sequence is
 // cancelled, depending on whether the site has a mobile-friendly viewport.
 // Note that these constants are effective only when the timeout is supported.
 const int kDesktopTouchAckTimeoutDelayMs = 200;
 const int kMobileTouchAckTimeoutDelayMs = 1000;
 
 TouchEventQueue::Config GetTouchEventQueueConfig() {
   TouchEventQueue::Config config;
 
   config.desktop_touch_ack_timeout_delay =
       base::TimeDelta::FromMilliseconds(kDesktopTouchAckTimeoutDelayMs);
   config.mobile_touch_ack_timeout_delay =
       base::TimeDelta::FromMilliseconds(kMobileTouchAckTimeoutDelayMs);
 
 #if defined(OS_ANDROID)
-  // For historical reasons only Android enables the touch ack timeout.
-  config.touch_ack_timeout_supported = true;
+  // For historical reasons only Android enables the touch ack timeout. The
+  // touch ack timeout will be replaced by an intervention which forces events
+  // to be non-blocking if the main thread is busy. This is currently behind a
+  // flag.
+  config.touch_ack_timeout_supported = !base::FeatureList::IsEnabled(
+      features::kMainThreadBusyScrollIntervention);
 #else
   config.touch_ack_timeout_supported = false;
 #endif
 
   return config;
 }
 
 GestureEventQueue::Config GetGestureEventQueueConfig() {
   GestureEventQueue::Config config;
   ui::GestureConfiguration* gesture_config =
@@ skipping 32 matching lines @@
 }  // namespace
 
 InputRouterImpl::Config GetInputRouterConfigForPlatform() {
   InputRouterImpl::Config config;
   config.gesture_config = GetGestureEventQueueConfig();
   config.touch_config = GetTouchEventQueueConfig();
   return config;
 }
 
 }  // namespace content