[Android] Always precede Tap gesture events with TapDown

content/common/input/gesture_event_stream_validator_unittest.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 "content/common/input/gesture_event_stream_validator.h"
 
 #include "content/common/input/synthetic_web_input_event_builders.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 using blink::WebInputEvent;
@@ skipping 163 matching lines @@
   EXPECT_TRUE(error_msg.empty());
 
   event = Build(WebInputEvent::GestureTapUnconfirmed);
   EXPECT_TRUE(validator.Validate(event, &error_msg));
   EXPECT_TRUE(error_msg.empty());
 
   event = Build(WebInputEvent::GestureTapCancel);
   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());
 }
 
 TEST(GestureEventStreamValidator, InvalidTap) {
   GestureEventStreamValidator validator;
   std::string error_msg;
   WebGestureEvent event;
 
   // No preceding TapDown.
   event = Build(WebInputEvent::GestureTapUnconfirmed);
   EXPECT_FALSE(validator.Validate(event, &error_msg));
   EXPECT_FALSE(error_msg.empty());
 
   event = Build(WebInputEvent::GestureTapCancel);
   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));
   EXPECT_TRUE(error_msg.empty());
 
   event = Build(WebInputEvent::GestureDoubleTap);
   EXPECT_TRUE(validator.Validate(event, &error_msg));
   EXPECT_TRUE(error_msg.empty());
 
   event = Build(WebInputEvent::GestureTapCancel);
   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));
   EXPECT_TRUE(error_msg.empty());
 
   event = Build(WebInputEvent::GestureTap);
   EXPECT_TRUE(validator.Validate(event, &error_msg));
   EXPECT_TRUE(error_msg.empty());
 
   event = Build(WebInputEvent::GestureTapCancel);
   EXPECT_FALSE(validator.Validate(event, &error_msg));
   EXPECT_FALSE(error_msg.empty());
 }
 
 }  // namespace content