Support tap_count in ui::GestureProvider.

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 fdc524bef2cf8e861fde0022dcf604db9fbf354f..f3b3bed5ad8369b9738a177a773c8ad3de98ef2c 100644
--- a/ui/events/gesture_detection/gesture_detector.cc
+++ b/ui/events/gesture_detection/gesture_detector.cc
@@ -64,7 +64,7 @@ void GestureDetector::SimpleGestureListener::OnShowPress(const MotionEvent& e) {
 }
 
 bool GestureDetector::SimpleGestureListener::OnSingleTapUp(
-    const MotionEvent& e) {
+    const MotionEvent& e, int tap_count) {

[jdduke (slow), 2014/05/21 15:07:14]

Maybe tap_repeat_count? Hmm, but that's slightly ambiguous...

[tdresser, 2014/05/21 16:39:15]

We use tap_count throughout (GestureEventDetails, PlatformGestureEvent,
WebInputEvent...)

   return false;
 }
 
@@ -100,7 +100,7 @@ bool GestureDetector::SimpleGestureListener::OnTwoFingerTap(
 }
 
 bool GestureDetector::SimpleGestureListener::OnSingleTapConfirmed(
-    const MotionEvent& e) {
+    const MotionEvent& e, int tap_count) {
   return false;
 }
 
@@ -187,9 +187,10 @@ GestureDetector::GestureDetector(
       last_focus_y_(0),
       down_focus_x_(0),
       down_focus_y_(0),
-  longpress_enabled_(true),
-  swipe_enabled_(false),
-  two_finger_tap_enabled_(false) {
+      longpress_enabled_(true),
+      swipe_enabled_(false),
+      two_finger_tap_enabled_(false),
+      tap_count_(0) {
   DCHECK(listener_);
   Init(config);
 }
@@ -327,6 +328,7 @@ bool GestureDetector::OnTouchEvent(const MotionEvent& ev) {
 
       down_focus_x_ = last_focus_x_ = focus_x;
       down_focus_y_ = last_focus_y_ = focus_y;
+      previous_down_event_ = current_down_event_.Pass();
       current_down_event_ = ev.Clone();
 
       secondary_pointer_down_event_.reset();
@@ -416,9 +418,27 @@ bool GestureDetector::OnTouchEvent(const MotionEvent& ev) {
           timeout_handler_->StopTimeout(TAP);
           in_longpress_ = false;
         } else if (always_in_tap_region_) {
-          handled = listener_->OnSingleTapUp(ev);
+          if (double_tap_listener_) {
+            tap_count_ = 1;
+          } else {
+            if (previous_down_event_ && previous_up_event_ &&
+                current_down_event_ &&
+                IsConsideredDoubleTap(*previous_down_event_,
+                                      *previous_up_event_,
+                                      *current_down_event_)) {
+              ++tap_count_;
+              // We only support up to triple tap. Further taps are also treated
+              // as triple taps.
+              tap_count_ = std::min(tap_count_, 3);

[jdduke (slow), 2014/05/21 15:07:14]

I'd prefer the GestureDetector not have any awareness of this restriction. 
Could we push this logic downstream?

[tdresser, 2014/05/21 16:39:15]

Done.

+            } else {
+              // As we're outside of the double tap range, reset the
+              // |tap_count_|.
+              tap_count_ = 1;
+            }
+          }
+          handled = listener_->OnSingleTapUp(ev, tap_count_);
           if (defer_confirm_single_tap_ && double_tap_listener_ != NULL) {
-            double_tap_listener_->OnSingleTapConfirmed(ev);
+            double_tap_listener_->OnSingleTapConfirmed(ev, 1);

[jdduke (slow), 2014/05/21 15:07:14]

Might as well just use |tap_count_| here instead of 1 for consistency.

[tdresser, 2014/05/21 16:39:15]

Done.

           }
         } else {
 
@@ -513,7 +533,7 @@ void GestureDetector::OnTapTimeout() {
   if (!double_tap_listener_)
     return;
   if (!still_down_)
-    double_tap_listener_->OnSingleTapConfirmed(*current_down_event_);
+    double_tap_listener_->OnSingleTapConfirmed(*current_down_event_, 1);
   else
     defer_confirm_single_tap_ = true;
 }