Remove windows/mac/ios specific code from //ui

ui/events/BUILD.gn

Index: ui/events/BUILD.gn
diff --git a/ui/events/BUILD.gn b/ui/events/BUILD.gn
index 41cd757520df1f6dcd24145d851ae2044c26253c..edb3c2260e129f63fbc1f6cd6c67c8e63387ddaf 100644
--- a/ui/events/BUILD.gn
+++ b/ui/events/BUILD.gn
@@ -37,8 +37,6 @@ component("events_base") {
     "keycodes/keyboard_code_conversion.h",
     "keycodes/keyboard_code_conversion_android.cc",
     "keycodes/keyboard_code_conversion_android.h",
-    "keycodes/keyboard_code_conversion_mac.h",
-    "keycodes/keyboard_code_conversion_mac.mm",
     "keycodes/keyboard_codes.h",
     "latency_info.cc",
     "latency_info.h",
@@ -87,7 +85,6 @@ component("events") {
     "gestures/gesture_recognizer.h",
     "gestures/gesture_recognizer_impl.cc",
     "gestures/gesture_recognizer_impl.h",
-    "gestures/gesture_recognizer_impl_mac.cc",
     "gestures/gesture_types.h",
     "gestures/motion_event_impl.cc",
     "gestures/motion_event_impl.h",
@@ -114,6 +111,7 @@ component("gesture_detection") {
     "gesture_detection/filtered_gesture_provider.cc",
     "gesture_detection/filtered_gesture_provider.h",
     "gesture_detection/gesture_config_helper.h",
+    "gesture_detection/gesture_config_helper_aura.cc",
     "gesture_detection/gesture_detection_export.h",
     "gesture_detection/gesture_detector.cc",
     "gesture_detection/gesture_detector.h",
@@ -141,11 +139,10 @@ component("gesture_detection") {
     "gesture_detection/snap_scroll_controller.h",
     "gesture_detection/touch_disposition_gesture_filter.cc",
     "gesture_detection/touch_disposition_gesture_filter.h",
-    "gesture_detection/velocity_tracker_state.cc",
-    "gesture_detection/velocity_tracker_state.h",
     "gesture_detection/velocity_tracker.cc",
     "gesture_detection/velocity_tracker.h",
-    "gesture_detection/gesture_config_helper_aura.cc",
+    "gesture_detection/velocity_tracker_state.cc",
+    "gesture_detection/velocity_tracker_state.h",
   ]
 
   deps = [
@@ -212,8 +209,8 @@ test("events_unittests") {
     "gestures/gesture_provider_impl_unittest.cc",
     "keycodes/dom4/keycode_converter_unittest.cc",
     "latency_info_unittest.cc",
-    "platform/platform_event_source_unittest.cc",
     "platform/platform_event_builder_x_unittest.cc",
+    "platform/platform_event_source_unittest.cc",
     "platform/x11/platform_event_utils_x_unittest.cc",
   ]