Adopt ui::GestureConfiguration on Android

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 "ui/gfx/android/view_configuration.h"
+#include "ui/gfx/screen.h"
+
+using gfx::ViewConfiguration;
+
+namespace ui {
+
+namespace {
+
+class GestureConfigurationAndroid : public GestureConfiguration {
+ public:
+  static GestureConfigurationAndroid* GetInstance() {
+    return Singleton<GestureConfigurationAndroid>::get();
+  }
+
+ private:
+  GestureConfigurationAndroid()
+      : GestureConfiguration(),
+        raw_pixel_to_dip_ratio_(1.f /
+                                gfx::Screen::GetNativeScreen()
+                                    ->GetPrimaryDisplay()
+                                    .device_scale_factor()) {
+    set_fling_velocity_cap(
+        ViewConfiguration::GetMaximumFlingVelocityInPixelsPerSecond() *
+        raw_pixel_to_dip_ratio_);
+    set_gesture_begin_end_types_enabled(false);
+    set_long_press_time_in_ms(ViewConfiguration::GetLongPressTimeoutInMs());
+    set_max_distance_between_taps_for_double_tap(

[jdduke (slow), 2014/10/22 17:31:34]

Should we also explicitly disable two_finger_tap and swipe?

[lanwei, 2014/10/23 01:26:18]

I feel if we already set false in the superclass, maybe it is fine that we do
not explicitly disable again.

+        ViewConfiguration::GetDoubleTapSlopInPixels() *
+        raw_pixel_to_dip_ratio_);
+    set_max_gesture_bounds_length(kMaxGestureBoundsLengthDips);
+    set_max_touch_move_in_pixels_for_click(
+        ViewConfiguration::GetTouchSlopInPixels() * raw_pixel_to_dip_ratio_);
+    set_min_gesture_bounds_length(kMinGestureBoundsLengthDips);
+    set_min_pinch_update_span_delta(0.f);
+    set_min_scaling_span_in_pixels(
+        ViewConfiguration::GetMinScalingSpanInPixels() *
+        raw_pixel_to_dip_ratio_);
+    set_min_scaling_touch_major(
+        ViewConfiguration::GetMinScalingTouchMajorInPixels() *
+        raw_pixel_to_dip_ratio_);
+    set_min_scroll_velocity(
+        ViewConfiguration::GetMinimumFlingVelocityInPixelsPerSecond() *
+        raw_pixel_to_dip_ratio_);
+    set_semi_long_press_time_in_ms(

[jdduke (slow), 2014/10/22 17:31:34]

Hmm, it seems a little odd to use the DoubleTap timeout for the semi_long_press,
what exactly is a semi_long_press on Aura?

[lanwei, 2014/10/23 01:26:18]

Done.

+        ViewConfiguration::GetDoubleTapTimeoutInMs());
+    set_show_press_delay_in_ms(ViewConfiguration::GetTapTimeoutInMs());
+    set_span_slop(ViewConfiguration::GetTouchSlopInPixels() * 2.f *
+                  raw_pixel_to_dip_ratio_);
+    set_display(gfx::Screen::GetNativeScreen()->GetPrimaryDisplay());

[jdduke (slow), 2014/10/22 17:31:34]

Yeah, I think we should avoid caching the Display, instead we can fetch it on
demand using gfx::Screen::GetNativeScreen()->GetPrimaryDisplay() when creating
the GestureProvider::Config.

[lanwei, 2014/10/23 01:26:18]

Done.

+  }
+
+  float raw_pixel_to_dip_ratio_;

[jdduke (slow), 2014/10/22 17:31:34]

Looks like this doesn't need to be a member variable.

[lanwei, 2014/10/23 01:26:18]

Done.

+
+  // This was the minimum tap/press size used on Android before the new gesture
+  // detection pipeline.
+  const float kMinGestureBoundsLengthDips = 24.f;

[jdduke (slow), 2014/10/22 17:31:34]

These constants should be pulled out of the class (you can just put them above
the class definition).

[lanwei, 2014/10/23 01:26:18]

Done.

+
+  // This value is somewhat arbitrary, but provides a reasonable maximum
+  // approximating a large thumb depression.
+  const float kMaxGestureBoundsLengthDips = kMinGestureBoundsLengthDips * 4.f;
+
+  friend struct DefaultSingletonTraits<GestureConfigurationAndroid>;
+  DISALLOW_COPY_AND_ASSIGN(GestureConfigurationAndroid);
+};
+
+}  // namespace
+
+GestureConfiguration* GestureConfiguration::GetInstance() {
+  return GestureConfigurationAndroid::GetInstance();
+}
+
+GestureProvider::Config DefaultGestureProviderConfig() {
+  return GestureConfigurationAndroid::GetInstance()
+      ->DefaultGestureProviderConfig();
+}
+
+}  // namespace ui