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..008feb237193c41e4fd8d36902d520605ad93b31 100644
--- a/content/browser/renderer_host/input/tap_suppression_controller.cc
+++ b/content/browser/renderer_host/input/tap_suppression_controller.cc
@@ -7,13 +7,27 @@
 #include "base/logging.h"
 #include "base/trace_event/trace_event.h"
 #include "content/browser/renderer_host/input/tap_suppression_controller_client.h"
+#include "ui/events/gesture_detection/gesture_configuration.h"
 
 namespace content {
 
+// The tapDownTimer is used to avoid waiting for an arbitrarily late fling
+// cancel ack. While the timer is running, if a fling cancel ack with
+// |Processed = false| arrives, all stashed gesture events get forwarded. If
+// the timer expires, the controller forwards stashed GestureTapDown only, and
+// drops the rest of the stashed events. The timer delay should be large enough
+// for a GestureLongPress to get stashed and forwarded if needed. It's still
+// possible for a GestureLongPress to arrive after the timer expiration. In
+// this case, it will be suppressed if the controller is in SUPPRESSING_TAPS
+// state.
+
 TapSuppressionController::Config::Config()
     : enabled(false),
-      max_cancel_to_down_time(base::TimeDelta::FromMilliseconds(180)),
-      max_tap_gap_time(base::TimeDelta::FromMilliseconds(500)) {
+      max_cancel_to_down_time(base::TimeDelta::FromMilliseconds(180)) {
+  ui::GestureConfiguration* gesture_config =
+      ui::GestureConfiguration::GetInstance();
+  max_tap_gap_time = base::TimeDelta::FromMilliseconds(
+      gesture_config->long_press_time_in_ms() + 50);
 }
 
 TapSuppressionController::TapSuppressionController(
@@ -34,6 +48,7 @@ void TapSuppressionController::GestureFlingCancel() {
     case NOTHING:
     case GFC_IN_PROGRESS:
     case LAST_CANCEL_STOPPED_FLING:
+    case SUPPRESSING_TAPS:
       state_ = GFC_IN_PROGRESS;
       break;
     case TAP_DOWN_STASHED:
@@ -46,6 +61,7 @@ void TapSuppressionController::GestureFlingCancelAck(bool processed) {
   switch (state_) {
     case DISABLED:
     case NOTHING:
+    case SUPPRESSING_TAPS:
       break;
     case GFC_IN_PROGRESS:
       if (processed)
@@ -57,7 +73,9 @@ 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 +107,10 @@ bool TapSuppressionController::ShouldDeferTapDown() {
         state_ = NOTHING;
         return false;
       }
+    // Stop suppressing tap end events.
+    case SUPPRESSING_TAPS:
+      state_ = NOTHING;
+      return false;
   }
   NOTREACHED() << "Invalid state";
   return false;
@@ -101,12 +123,17 @@ 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, change the state
+      // to "SUPPRESSING_TAPS" when the stashed tap down is dropped.
+      state_ = SUPPRESSING_TAPS;
       StopTapDownTimer();
       client_->DropStashedTapDown();
       return true;
     case LAST_CANCEL_STOPPED_FLING:
       NOTREACHED() << "Invalid tap end on LAST_CANCEL_STOPPED_FLING state";
+    case SUPPRESSING_TAPS:
+      return true;
   }
   return false;
 }
@@ -128,6 +155,7 @@ void TapSuppressionController::TapDownTimerExpired() {
   switch (state_) {
     case DISABLED:
     case NOTHING:
+    case SUPPRESSING_TAPS:
       NOTREACHED() << "Timer fired on invalid state.";
       break;
     case GFC_IN_PROGRESS:
@@ -138,8 +166,10 @@ 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_ = SUPPRESSING_TAPS;
       break;
   }
 }