[Android] Select text when stylus first button is pressed.

ui/events/BUILD.gn

Index: ui/events/BUILD.gn
diff --git a/ui/events/BUILD.gn b/ui/events/BUILD.gn
index 97122e6f9bca86496996fca5d817e053b4279cec..c49b3355c27ccca951f791a889ba1cc9692c7c26 100644
--- a/ui/events/BUILD.gn
+++ b/ui/events/BUILD.gn
@@ -268,6 +268,18 @@ source_set("events_test_support") {
   }
 }
 
+static_library("mock_motion_event") {
+  sources = [
+    "gesture_detection/mock_motion_event.h",
+    "gesture_detection/mock_motion_event.cc",
+  ]
+
+  deps = [
+    "//base",
+    ":gesture_detection",
+  ]
+}
+
 test("events_unittests") {
   sources = [
     "cocoa/events_mac_unittest.mm",
@@ -278,8 +290,6 @@ test("events_unittests") {
     "gestures/velocity_calculator_unittest.cc",
     "gesture_detection/bitset_32_unittest.cc",
     "gesture_detection/gesture_provider_unittest.cc",
-    "gesture_detection/mock_motion_event.h",
-    "gesture_detection/mock_motion_event.cc",
     "gesture_detection/velocity_tracker_unittest.cc",
     "gesture_detection/touch_disposition_gesture_filter_unittest.cc",
     "keycodes/dom4/keycode_converter_unittest.cc",
@@ -306,6 +316,7 @@ test("events_unittests") {
     ":events_base",
     ":events_test_support",
     ":gesture_detection",
+    ":mock_motion_event",
     "//base",
     "//base/test:run_all_unittests",
     "//skia",