[Android] Always precede Tap gesture events with TapDown

content/common/input/gesture_event_stream_validator_unittest.cc

Index: content/common/input/gesture_event_stream_validator_unittest.cc
diff --git a/content/common/input/gesture_event_stream_validator_unittest.cc b/content/common/input/gesture_event_stream_validator_unittest.cc
index 857dcfe9375e8f898e08b85b7b4c626e87afab84..590b1884e11c800a2723d3036240dd063f64a2bf 100644
--- a/content/common/input/gesture_event_stream_validator_unittest.cc
+++ b/content/common/input/gesture_event_stream_validator_unittest.cc
@@ -181,12 +181,16 @@ TEST(GestureEventStreamValidator, ValidTap) {
   EXPECT_TRUE(validator.Validate(event, &error_msg));
   EXPECT_TRUE(error_msg.empty());
 
-  // Tap and DoubleTap do not require a TapDown (unlike TapUnconfirmed and
-  // TapCancel).
+  event = Build(WebInputEvent::GestureTapDown);
+  EXPECT_TRUE(validator.Validate(event, &error_msg));
+  EXPECT_TRUE(error_msg.empty());
+
   event = Build(WebInputEvent::GestureTap);
   EXPECT_TRUE(validator.Validate(event, &error_msg));
   EXPECT_TRUE(error_msg.empty());
 
+  // DoubleTap does not require a TapDown (unlike Tap, TapUnconfirmed and
+  // TapCancel).
   event = Build(WebInputEvent::GestureDoubleTap);
   EXPECT_TRUE(validator.Validate(event, &error_msg));
   EXPECT_TRUE(error_msg.empty());
@@ -206,6 +210,10 @@ TEST(GestureEventStreamValidator, InvalidTap) {
   EXPECT_FALSE(validator.Validate(event, &error_msg));
   EXPECT_FALSE(error_msg.empty());
 
+  event = Build(WebInputEvent::GestureTap);
+  EXPECT_FALSE(validator.Validate(event, &error_msg));
+  EXPECT_FALSE(error_msg.empty());
+
   // TapDown already terminated.
   event = Build(WebInputEvent::GestureTapDown);
   EXPECT_TRUE(validator.Validate(event, &error_msg));