Disable tap suppression logic for WebView

ui/events/gesture_detection/gesture_configuration_android.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/events/gesture_detection/gesture_configuration.h"
 
 #include "base/memory/singleton.h"
 #include "ui/gfx/android/view_configuration.h"
 #include "ui/gfx/screen.h"
 
@@ skipping 34 matching lines @@
     set_min_fling_velocity(
         ViewConfiguration::GetMinimumFlingVelocityInDipsPerSecond());
     set_min_gesture_bounds_length(kMinGestureBoundsLengthDips);
     set_min_pinch_update_span_delta(0.f);
     set_min_scaling_span_in_pixels(
         ViewConfiguration::GetMinScalingSpanInDips());
     set_min_scaling_touch_major(
         ViewConfiguration::GetMinScalingTouchMajorInDips());
     set_show_press_delay_in_ms(ViewConfiguration::GetTapTimeoutInMs());
     set_span_slop(ViewConfiguration::GetTouchSlopInDips() * 2.f);
+    set_fling_touchscreen_tap_suppression_enabled(true);
+    set_fling_touchpad_tap_suppression_enabled(false);

[tdresser, 2015/08/04 12:20:50]

If you plug in an external touchpad on Android, do you get fling behavior?

[jdduke (slow), 2015/08/04 17:19:25]

I don't actually know =/, I was about to order an Apple magic trackpad. We would
never get a fling event I don't think, but I wonder if the OS handles such
touchpad flings, or maybe it's even lower level like the driver/firmware (like
on Windows)? We can always enable it when we find the right scenario (though, I
don't think we ever send mouedown/mouseup events yet on Android, so this
probably wouldn't do anything yet).

+    set_fling_max_cancel_to_down_time_in_ms(
+        ViewConfiguration::GetTapTimeoutInMs());
+    set_fling_max_tap_gap_time_in_ms(
+        ViewConfiguration::GetLongPressTimeoutInMs());
+    // There is no "semi" longpress on Android, just use the longpress value.

[tdresser, 2015/08/04 12:20:50]

I think it might be clearer to set this to 0.

[jdduke (slow), 2015/08/04 17:19:25]

Yeah, I went ahead and removed this line, and changed the tap configuration
logic so it uses long_press_time_in_ms instead.

+    set_semi_long_press_time_in_ms(
+        ViewConfiguration::GetLongPressTimeoutInMs());
   }
 
   friend struct DefaultSingletonTraits<GestureConfigurationAndroid>;
   DISALLOW_COPY_AND_ASSIGN(GestureConfigurationAndroid);
 };
 
 }  // namespace
 
 // Create a GestureConfigurationAura singleton instance when using Android.
 GestureConfiguration* GestureConfiguration::GetPlatformSpecificInstance() {
   return GestureConfigurationAndroid::GetInstance();
 }
 
 }  // namespace ui