Suppress LongPress/Tap, and TwoFingerTap when TapDown cancels a fling.

content/browser/renderer_host/input/tap_suppression_controller.cc

Index: content/browser/renderer_host/input/tap_suppression_controller.cc
diff --git a/content/browser/renderer_host/input/tap_suppression_controller.cc b/content/browser/renderer_host/input/tap_suppression_controller.cc
index 78b3a076d6d40b1b0db7f2c18cdb58fbb0c4f55a..686a413e2f5aa600598bd2373b8d949250f42cc8 100644
--- a/content/browser/renderer_host/input/tap_suppression_controller.cc
+++ b/content/browser/renderer_host/input/tap_suppression_controller.cc
@@ -13,7 +13,7 @@ namespace content {
 TapSuppressionController::Config::Config()
     : enabled(false),
       max_cancel_to_down_time(base::TimeDelta::FromMilliseconds(180)),
-      max_tap_gap_time(base::TimeDelta::FromMilliseconds(500)) {
+      max_tap_gap_time(base::TimeDelta::FromMilliseconds(550)) {

[tdresser, 2016/12/01 18:57:59]

Why this change? This constant likely needs a comment.

[sahel, 2016/12/06 15:18:13]

This is set to 500ms, because that's the long press timeout (the longest
timeout)
I changed it to 550 because it should be larger than the long press timeout to
suppress it.

 }
 
 TapSuppressionController::TapSuppressionController(
@@ -34,6 +34,7 @@ void TapSuppressionController::GestureFlingCancel() {
     case NOTHING:
     case GFC_IN_PROGRESS:
     case LAST_CANCEL_STOPPED_FLING:
+    case MUST_SUPPRESS_TAP_ENDS:
       state_ = GFC_IN_PROGRESS;
       break;
     case TAP_DOWN_STASHED:
@@ -46,6 +47,7 @@ void TapSuppressionController::GestureFlingCancelAck(bool processed) {
   switch (state_) {
     case DISABLED:
     case NOTHING:
+    case MUST_SUPPRESS_TAP_ENDS:
       break;
     case GFC_IN_PROGRESS:
       if (processed)
@@ -57,7 +59,9 @@ void TapSuppressionController::GestureFlingCancelAck(bool processed) {
         TRACE_EVENT0("browser",
                      "TapSuppressionController::GestureFlingCancelAck");
         StopTapDownTimer();
-        client_->ForwardStashedTapDown();
+        // If the fling cancel is not processed, forward all stashed
+        // gesture events.
+        client_->ForwardStashedGestureEvents();
         state_ = NOTHING;
       }  // Else waiting for the timer to release the stashed tap down.
       break;
@@ -89,6 +93,10 @@ bool TapSuppressionController::ShouldDeferTapDown() {
         state_ = NOTHING;
         return false;
       }
+    // Stop suppressing tap end events.
+    case MUST_SUPPRESS_TAP_ENDS:
+      state_ = NOTHING;
+      return false;
   }
   NOTREACHED() << "Invalid state";
   return false;
@@ -101,12 +109,17 @@ bool TapSuppressionController::ShouldSuppressTapEnd() {
     case GFC_IN_PROGRESS:
       return false;
     case TAP_DOWN_STASHED:
-      state_ = NOTHING;
+      // A tap cancel happens before long tap and two finger tap events. To
+      // drop the latter events as well as the tap cancel, don't change the
+      // state to NOTHING when the stashed tap down is dropped.

[tdresser, 2016/12/01 18:57:59]

This comment feels related to the history of the file, which is a bit confusing.

I'd say "to drop the latter events as well as the tap cancel, change the state
to MUST_SUPPRESS_TAP_ENDS" when the stashed tap down is dropped.

[sahel, 2016/12/06 15:18:13]

Done.

+      state_ = MUST_SUPPRESS_TAP_ENDS;
       StopTapDownTimer();
       client_->DropStashedTapDown();
       return true;
     case LAST_CANCEL_STOPPED_FLING:
       NOTREACHED() << "Invalid tap end on LAST_CANCEL_STOPPED_FLING state";
+    case MUST_SUPPRESS_TAP_ENDS:
+      return true;
   }
   return false;
 }
@@ -128,6 +141,7 @@ void TapSuppressionController::TapDownTimerExpired() {
   switch (state_) {
     case DISABLED:
     case NOTHING:
+    case MUST_SUPPRESS_TAP_ENDS:
       NOTREACHED() << "Timer fired on invalid state.";
       break;
     case GFC_IN_PROGRESS:
@@ -138,8 +152,10 @@ void TapSuppressionController::TapDownTimerExpired() {
     case TAP_DOWN_STASHED:
       TRACE_EVENT0("browser",
                    "TapSuppressionController::TapDownTimerExpired");
+      // When the timer expires, only forward the stashed tap down event, and
+      // drop other stashed gesture events (show press or long press).
       client_->ForwardStashedTapDown();
-      state_ = NOTHING;
+      state_ = MUST_SUPPRESS_TAP_ENDS;
       break;
   }
 }