Add a TouchEventStreamValidator

content/common/input/touch_event_stream_validator.h

Index: content/common/input/touch_event_stream_validator.h
diff --git a/content/common/input/touch_event_stream_validator.h b/content/common/input/touch_event_stream_validator.h
new file mode 100644
index 0000000000000000000000000000000000000000..0c9732cedfd35e896eb45335d5e7a6c372dba284
--- /dev/null
+++ b/content/common/input/touch_event_stream_validator.h
@@ -0,0 +1,33 @@
+// 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.
+
+#ifndef CONTENT_COMMON_INPUT_TOUCH_EVENT_STREAM_VALIDATOR
+#define CONTENT_COMMON_INPUT_TOUCH_EVENT_STREAM_VALIDATOR
+
+#include <string>
+
+#include "base/basictypes.h"
+#include "third_party/WebKit/public/web/WebInputEvent.h"
+
+namespace content {
+
+// Utility class for validating a stream of WebTouchEvents.
+class TouchEventStreamValidator {
+ public:
+  TouchEventStreamValidator();
+  ~TouchEventStreamValidator();
+
+  // If |event| is valid for the current stream, returns true.
+  // Otherwise, returns false with a corresponding error message.
+  bool Validate(const blink::WebTouchEvent& event, std::string* error_msg);
+
+ private:
+  blink::WebTouchEvent previous_event_;
+
+  DISALLOW_COPY_AND_ASSIGN(TouchEventStreamValidator);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_COMMON_INPUT_TOUCH_EVENT_STREAM_VALIDATOR