This patch implements Chromium's Aura gesture recognizer in terms of utouch-grail and utouch-frame …

ui/aura/gestures/gesture_recognizer_grail.h

+// Copyright (c) 2012 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_AURA_GESTURES_GESTURE_RECOGNIZER_GRAIL_H_
+#define UI_AURA_GESTURES_GESTURE_RECOGNIZER_GRAIL_H_
+#pragma once
+
+#include "ui/aura/gestures/gesture_recognizer.h"
+

[Elliot Glaysher, 2012/03/28 17:49:00]

Add "base/compiler_specific.h" for the OVERRIDE macro

+#include "base/memory/linked_ptr.h"
+#include "base/memory/scoped_ptr.h"
+#include "ui/aura/aura_export.h"
+#include "ui/base/events.h"
+
+#include <map>

[sky, 2012/03/28 20:30:36]

Include order is wrong here. For a header you want system includes, then
non-system includes.

+#include <queue>
+#include <vector>
+
+namespace aura {
+class GestureEvent;
+class TouchEvent;
+class Window;
+
+// A GestureRecognizer is an abstract base class for
+// conversion of touch events into gestures.
+class AURA_EXPORT GestureRecognizerGrail : public GestureRecognizer {

[sky, 2012/03/28 20:30:36]

Why do we need both a GestureRecognizer and GestureRecognizerGrail?

+ public:
+  explicit GestureRecognizerGrail(RootWindow* window = NULL);
+
+  // Invoked for each touch event that could contribute to
+  // the current gesture.
+  // Returns list of  zero or more GestureEvents identified after processing
+  // TouchEvent.
+  // Caller would be responsible for freeing up Gestures.
+  virtual GestureRecognizer::Gestures*
+      ProcessTouchEventForGesture(const TouchEvent& event,
+                                  ui::TouchStatus status);

[Elliot Glaysher, 2012/03/28 17:49:00]

OVERRIDE on all virtual methods that you're overriding.

+
+  void QueueTouchEventForGesture(Window* window,
+                                 const TouchEvent& event) {
+    // Implemented empty
+  }
+
+  void FlushTouchQueue(Window* window) {
+    // Implemented empty
+  }
+
+  virtual Gestures* AdvanceTouchQueue(Window* window,

[Elliot Glaysher, 2012/03/28 17:49:00]

virtual methods with nonempty bodies go in impl. we have a bot that checks for
this. Also OVERRIDE on the signature.

+                                      bool processed) {
+    return NULL;
+  }
+
+ private:
+  struct Private;
+  scoped_ptr<Private> d_;
+
+  DISALLOW_COPY_AND_ASSIGN(GestureRecognizerGrail);
+};
+}  // namespace aura
+
+#endif  // UI_AURA_GESTURES_GESTURE_RECOGNIZER_GRAIL_H_