Add support for new scroll valuators coming from CMT

ui/base/x/scroll_factory.h

+// Copyright (c) 2011 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 UI_BASE_X_SCROLL_FACTORY_H_
+#define UI_BASE_X_SCROLL_FACTORY_H_
+#pragma once
+
+#include <bitset>
+#include <map>
+
+#include "base/memory/singleton.h"
+#include "ui/base/ui_export.h"
+
+typedef struct _XDisplay Display;
+typedef union _XEvent XEvent;
+
+namespace ui {
+
+// A class to support the detection of scroll events, using X11 valuators.
+class UI_EXPORT ScrollFactory {
+ public:
+  // Returns the ScrollFactory singleton.
+  static ScrollFactory* GetInstance();
+
+  // Updates the list of devices.
+  void UpdateDeviceList(Display* display);
+
+  // Returns true if this is a scroll event (a motion event with the necessary
+  // valuators. Also returns the offsets. |x_offset| and |y_offset| can be
+  // NULL.
+  bool GetScrollOffsets(const XEvent& xev, float* x_offset, float* y_offset);
+
+ private:
+  ScrollFactory();
+  ~ScrollFactory();
+  // Requirement for Signleton

[Ben Goodger (Google), 2011/12/14 19:01:39]

nit: I believe your type definitions have to go before the ctors/other
functions.

[DaveMoore, 2011/12/14 21:26:04]

Done.

+  friend struct DefaultSingletonTraits<ScrollFactory>;
+  struct Valuators {
+    int x_scroll;
+    int y_scroll;
+  };
+
+  // A quick lookup table for determining if events from the pointer device
+  // should be processed.
+  static const int kMaxDeviceNum = 128;
+  std::bitset<kMaxDeviceNum> scroll_devices_;
+  std::map<int, Valuators> device_to_valuators_;
+};
+
+}  // namespace ui
+
+#endif  // UI_BASE_X_SCROLL_FACTORY_H_