scheduler: Detect single event gestures correctly

third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl.cc

Index: third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl.cc
diff --git a/third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl.cc b/third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl.cc
index 130d539b4ef053726821e1968e10753b6c00ba7e..cb4938dc6b74f1baa9047d51c1c9c05ee59111f0 100644
--- a/third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl.cc
+++ b/third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl.cc
@@ -757,7 +757,8 @@ void RendererSchedulerImpl::UpdateForInputEventOnCompositorThread(
 }
 
 void RendererSchedulerImpl::DidHandleInputEventOnMainThread(
-    const blink::WebInputEvent& web_input_event) {
+    const WebInputEvent& web_input_event,
+    WebInputEventResult result) {
   TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("renderer.scheduler"),
                "RendererSchedulerImpl::DidHandleInputEventOnMainThread");
   helper_.CheckOnValidThread();
@@ -765,6 +766,17 @@ void RendererSchedulerImpl::DidHandleInputEventOnMainThread(
     base::AutoLock lock(any_thread_lock_);
     AnyThread().user_model.DidFinishProcessingInputEvent(
         helper_.scheduler_tqm_delegate()->NowTicks());
+
+    // If we were waiting for a touchstart response and the main thread has
+    // prevented the default gesture, consider the gesture established. This
+    // ensures single-event gestures such as button presses are promptly
+    // detected.
+    if (AnyThread().awaiting_touch_start_response &&
+        result == WebInputEventResult::HandledApplication) {
+      AnyThread().awaiting_touch_start_response = false;
+      AnyThread().default_gesture_prevented = true;
+      UpdatePolicyLocked(UpdateType::MAY_EARLY_OUT_IF_POLICY_UNCHANGED);
+    }
   }
 }