Touch emulator: allow multiple touch streams.

content/browser/renderer_host/input/touch_stream_tracker.h

+// 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_BROWSER_RENDERER_HOST_INPUT_TOUCH_STREAM_TRACKER_H_
+#define CONTENT_BROWSER_RENDERER_HOST_INPUT_TOUCH_STREAM_TRACKER_H_
+
+#include "content/browser/renderer_host/event_with_latency_info.h"
+#include "content/common/input/input_event_ack_state.h"
+#include "third_party/WebKit/public/web/WebInputEvent.h"
+
+namespace content {
+
+// Tracks multiple touch streams and filters events from all other streams
+// while one is active.
+class CONTENT_EXPORT TouchStreamTracker {
+ public:
+  enum TouchStream {
+    NATIVE_STREAM,
+    EMULATED_STREAM
+  };
+
+  TouchStreamTracker();
+  virtual ~TouchStreamTracker();
+
+  // Tracker may immediately ack touch event if another touch stream is active.
+  InputEventAckState FilterTouchEventFromStream(
+      const blink::WebTouchEvent& touch_event, TouchStream stream);
+
+  // Returns the touch stream which should receive this ack.
+  TouchStream OnTouchEventAck(
+      const TouchEventWithLatencyInfo& event, InputEventAckState ack_result);
+
+ private:
+  bool has_active_touch_stream_;
+  TouchStream active_touch_stream_;
+
+  DISALLOW_COPY_AND_ASSIGN(TouchStreamTracker);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_RENDERER_HOST_INPUT_TOUCH_EMULATOR_H_