[Android] Support double-tap selection

ui/events/gesture_detection/gesture_detector.cc

Index: ui/events/gesture_detection/gesture_detector.cc
diff --git a/ui/events/gesture_detection/gesture_detector.cc b/ui/events/gesture_detection/gesture_detector.cc
index 4180eb3338085423cc09ae1549493f58e06c26a6..bc9c7dfc6fbfd3bbe73df851bf50b2c968a625d6 100644
--- a/ui/events/gesture_detection/gesture_detector.cc
+++ b/ui/events/gesture_detection/gesture_detector.cc
@@ -55,8 +55,8 @@ GestureDetector::Config::Config()
       two_finger_tap_enabled(false),
       two_finger_tap_max_separation(300),
       two_finger_tap_timeout(base::TimeDelta::FromMilliseconds(700)),
-      velocity_tracker_strategy(VelocityTracker::Strategy::STRATEGY_DEFAULT) {
-}
+      single_tap_repeat_length(1),
+      velocity_tracker_strategy(VelocityTracker::Strategy::STRATEGY_DEFAULT) {}
 
 GestureDetector::Config::~Config() {}
 
@@ -129,6 +129,8 @@ GestureDetector::GestureDetector(
       always_in_bigger_tap_region_(false),
       two_finger_tap_allowed_for_gesture_(false),
       is_double_tapping_(false),
+      single_tap_count_(1),
+      single_tap_repeat_length_(1),
       last_focus_x_(0),
       last_focus_y_(0),
       down_focus_x_(0),
@@ -234,14 +236,16 @@ bool GestureDetector::OnTouchEvent(const MotionEvent& ev) {
       two_finger_tap_allowed_for_gesture_ = false;
     } break;
 
-    case MotionEvent::ACTION_DOWN:
+    case MotionEvent::ACTION_DOWN: {
+      bool maybe_double_tapping =
+          current_down_event_ && previous_up_event_ &&
+          IsConsideredDoubleTap(*current_down_event_, *previous_up_event_, ev);
       if (double_tap_listener_) {
+        single_tap_count_ = 1;
         bool had_tap_message = timeout_handler_->HasTimeout(TAP);
         if (had_tap_message)
           timeout_handler_->StopTimeout(TAP);
-        if (current_down_event_ && previous_up_event_ && had_tap_message &&
-            IsConsideredDoubleTap(
-                *current_down_event_, *previous_up_event_, ev)) {
+        if (maybe_double_tapping && had_tap_message) {
           // This is a second tap.
           is_double_tapping_ = true;
           // Give a callback with the first tap of the double-tap.
@@ -253,6 +257,8 @@ bool GestureDetector::OnTouchEvent(const MotionEvent& ev) {
           DCHECK(double_tap_timeout_ > base::TimeDelta());
           timeout_handler_->StartTimeout(TAP);
         }
+      } else if (maybe_double_tapping) {
+        single_tap_count_ = 1 + (single_tap_count_ % single_tap_repeat_length_);
       }
 
       down_focus_x_ = last_focus_x_ = focus_x;
@@ -273,7 +279,7 @@ bool GestureDetector::OnTouchEvent(const MotionEvent& ev) {
       if (longpress_enabled_)
         timeout_handler_->StartTimeout(LONG_PRESS);
       handled |= listener_->OnDown(ev);
-      break;
+    } break;
 
     case MotionEvent::ACTION_MOVE:
       {
@@ -343,12 +349,12 @@ bool GestureDetector::OnTouchEvent(const MotionEvent& ev) {
           DCHECK(double_tap_listener_);
           handled |= double_tap_listener_->OnDoubleTapEvent(ev);
         } else if (always_in_tap_region_) {
-          handled = listener_->OnSingleTapUp(ev);
+          handled = listener_->OnSingleTapUp(ev, single_tap_count_);
           if (defer_confirm_single_tap_ && double_tap_listener_ != NULL) {
             double_tap_listener_->OnSingleTapConfirmed(ev);
           }
         } else {
-
+          single_tap_count_ = 1;
           // A fling must travel the minimum tap distance.
           const int pointer_id = ev.GetPointerId(0);
           velocity_tracker_.ComputeCurrentVelocity(1000, max_fling_velocity_);
@@ -428,6 +434,9 @@ void GestureDetector::Init(const Config& config) {
   two_finger_tap_distance_square_ = config.two_finger_tap_max_separation *
                                     config.two_finger_tap_max_separation;
   two_finger_tap_timeout_ = config.two_finger_tap_timeout;
+
+  DCHECK_GE(config.single_tap_repeat_length, 1);
+  single_tap_repeat_length_ = config.single_tap_repeat_length;
 }
 
 void GestureDetector::OnShowPressTimeout() {
@@ -463,6 +472,7 @@ void GestureDetector::CancelTaps() {
   always_in_tap_region_ = false;
   always_in_bigger_tap_region_ = false;
   defer_confirm_single_tap_ = false;
+  single_tap_count_ = 1;
 }
 
 bool GestureDetector::IsConsideredDoubleTap(