[NOT FOR REVIEW] Patch demonstrating the changes required for browser side fling.

content/browser/renderer_host/input/gesture_event_filter.h

Index: content/browser/renderer_host/input/gesture_event_filter.h
diff --git a/content/browser/renderer_host/input/gesture_event_filter.h b/content/browser/renderer_host/input/gesture_event_filter.h
deleted file mode 100644
index 62949fbb2720457067343d52e5f57b423cff5d2b..0000000000000000000000000000000000000000
--- a/content/browser/renderer_host/input/gesture_event_filter.h
+++ /dev/null
@@ -1,224 +0,0 @@
-// Copyright 2013 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_GESTURE_EVENT_FILTER_H_
-#define CONTENT_BROWSER_RENDERER_HOST_INPUT_GESTURE_EVENT_FILTER_H_
-
-#include <deque>
-
-#include "base/basictypes.h"
-#include "base/memory/scoped_ptr.h"
-#include "base/timer/timer.h"
-#include "content/common/content_export.h"
-#include "content/port/browser/event_with_latency_info.h"
-#include "content/port/common/input_event_ack_state.h"
-#include "third_party/WebKit/public/web/WebInputEvent.h"
-#include "ui/gfx/transform.h"
-
-namespace content {
-class GestureEventFilterTest;
-class InputRouter;
-class MockRenderWidgetHost;
-class TouchpadTapSuppressionController;
-class TouchpadTapSuppressionControllerClient;
-class TouchscreenTapSuppressionController;
-
-// Interface with which the GestureEventFilter can forward gesture events, and
-// dispatch gesture event responses.
-class CONTENT_EXPORT GestureEventFilterClient {
- public:
-  virtual ~GestureEventFilterClient() {}
-
-  virtual void SendGestureEventImmediately(
-      const GestureEventWithLatencyInfo& event) = 0;
-
-  virtual void OnGestureEventAck(
-      const GestureEventWithLatencyInfo& event,
-      InputEventAckState ack_result) = 0;
-};
-
-// Maintains WebGestureEvents in a queue before forwarding them to the renderer
-// to apply a sequence of filters on them:
-// 1. Zero-velocity fling-starts from touchpad are filtered.
-// 2. The sequence is filtered for bounces. A bounce is when the finger lifts
-//    from the screen briefly during an in-progress scroll. Ifco this happens,
-//    non-GestureScrollUpdate events are queued until the de-bounce interval
-//    passes or another GestureScrollUpdate event occurs.
-// 3. Unnecessary GestureFlingCancel events are filtered. These are
-//    GestureFlingCancels that have no corresponding GestureFlingStart in the
-//    queue.
-// 4. Taps immediately after a GestureFlingCancel (caused by the same tap) are
-//    filtered.
-// 5. Whenever possible, events in the queue are coalesced to have as few events
-//    as possible and therefore maximize the chance that the event stream can be
-//    handled entirely by the compositor thread.
-// Events in the queue are forwarded to the renderer one by one; i.e., each
-// event is sent after receiving the ACK for previous one. The only exception is
-// that if a GestureScrollUpdate is followed by a GesturePinchUpdate, they are
-// sent together.
-// TODO(rjkroege): Possibly refactor into a filter chain:
-// http://crbug.com/148443.
-class CONTENT_EXPORT GestureEventFilter {
- public:
-  // Both |client| and |touchpad_client| must outlive the GestureEventFilter.
-  GestureEventFilter(GestureEventFilterClient* client,
-                     TouchpadTapSuppressionControllerClient* touchpad_client);
-  ~GestureEventFilter();
-
-  // Returns |true| if the caller should immediately forward the provided
-  // |GestureEventWithLatencyInfo| argument to the renderer.
-  bool ShouldForward(const GestureEventWithLatencyInfo&);
-
-  // Indicates that the caller has received an acknowledgement from the renderer
-  // with state |ack_result| and event |type|. May send events if the queue is
-  // not empty.
-  void ProcessGestureAck(InputEventAckState ack_result,
-                         WebKit::WebInputEvent::Type type,
-                         const ui::LatencyInfo& latency);
-
-  // Sets the state of the |fling_in_progress_| field to indicate that a fling
-  // is definitely not in progress.
-  void FlingHasBeenHalted();
-
-  // Returns the |TouchpadTapSuppressionController| instance.
-  TouchpadTapSuppressionController* GetTouchpadTapSuppressionController();
-
-  // Returns whether there are any gesture event in the queue.
-  bool HasQueuedGestureEvents() const;
-
-  void ForwardGestureEvent(const GestureEventWithLatencyInfo& gesture_event);
-
- private:
-  friend class MockRenderWidgetHost;
-  friend class GestureEventFilterTest;
-
-  static bool ShouldIgnoreAckForGestureType(WebKit::WebInputEvent::Type type);
-
-  // Returns the last gesture event that was sent to the renderer.
-  const GestureEventWithLatencyInfo& GetGestureEventAwaitingAck() const;
-
-  // TODO(mohsen): There are a bunch of ShouldForward.../ShouldDiscard...
-  // methods that are getting confusing. This should be somehow fixed. Maybe
-  // while refactoring GEF: http://crbug.com/148443.
-
-  // Inovked on the expiration of the debounce interval to release
-  // deferred events.
-  void SendScrollEndingEventsNow();
-
-  // Returns |true| if the given GestureFlingCancel should be discarded
-  // as unnecessary.
-  bool ShouldDiscardFlingCancelEvent(
-      const GestureEventWithLatencyInfo& gesture_event) const;
-
-  // Returns |true| if the only event in the queue is the current event and
-  // hence that event should be handled now.
-  bool ShouldHandleEventNow() const;
-
-  // Merge or append a GestureScrollUpdate or GesturePinchUpdate into
-  // the coalescing queue.
-  void MergeOrInsertScrollAndPinchEvent(
-      const GestureEventWithLatencyInfo& gesture_event);
-
-  // Sub-filter for removing zero-velocity fling-starts from touchpad.
-  bool ShouldForwardForZeroVelocityFlingStart(
-      const GestureEventWithLatencyInfo& gesture_event) const;
-
-  // Sub-filter for removing bounces from in-progress scrolls.
-  bool ShouldForwardForBounceReduction(
-      const GestureEventWithLatencyInfo& gesture_event);
-
-  // Sub-filter for removing unnecessary GestureFlingCancels.
-  bool ShouldForwardForGFCFiltering(
-      const GestureEventWithLatencyInfo& gesture_event) const;
-
-  // Sub-filter for suppressing taps immediately after a GestureFlingCancel.
-  bool ShouldForwardForTapSuppression(
-      const GestureEventWithLatencyInfo& gesture_event);
-
-  // Puts the events in a queue to forward them one by one; i.e., forward them
-  // whenever ACK for previous event is received. This queue also tries to
-  // coalesce events as much as possible.
-  bool ShouldForwardForCoalescing(
-      const GestureEventWithLatencyInfo& gesture_event);
-
-  // Whether the event_in_queue is GesturePinchUpdate or
-  // GestureScrollUpdate and it has the same modifiers as the
-  // new event.
-  bool ShouldTryMerging(
-      const GestureEventWithLatencyInfo& new_event,
-      const GestureEventWithLatencyInfo& event_in_queue)const;
-
-  // Returns the transform matrix corresponding to the gesture event.
-  // Assumes the gesture event sent is either GestureScrollUpdate or
-  // GesturePinchUpdate. Returns the identity matrix otherwise.
-  gfx::Transform GetTransformForEvent(
-      const GestureEventWithLatencyInfo& gesture_event) const;
-
-  // Pops and sends events ignoring ack from the head of
-  // |coalesced_gesture_events_| until the queue is empty or the event at the
-  // head requires an ack.
-  void SendEventsIgnoringAck();
-
-  // Adds |gesture_event| to the |coalesced_gesture_events_|, resetting the
-  // accumulation of |combined_scroll_pinch_|.
-  void EnqueueEvent(const GestureEventWithLatencyInfo& gesture_event);
-
-  // The receiver of all forwarded gesture events.
-  GestureEventFilterClient* client_;
-
-  // True if a GestureFlingStart is in progress on the renderer or
-  // queued without a subsequent queued GestureFlingCancel event.
-  bool fling_in_progress_;
-
-  // True if a GestureScrollUpdate sequence is in progress.
-  bool scrolling_in_progress_;
-
-  // True if two related gesture events were sent before without waiting
-  // for an ACK, so the next gesture ACK should be ignored.
-  bool ignore_next_ack_;
-
-  // Transform that holds the combined transform matrix for the current
-  // scroll-pinch sequence at the end of the queue.
-  gfx::Transform combined_scroll_pinch_;
-
-  // An object tracking the state of touchpad on the delivery of mouse events to
-  // the renderer to filter mouse immediately after a touchpad fling canceling
-  // tap.
-  // TODO(mohsen): Move touchpad tap suppression out of GestureEventFilter since
-  // GEF is meant to only be used for touchscreen gesture events.
-  scoped_ptr<TouchpadTapSuppressionController>
-      touchpad_tap_suppression_controller_;
-
-  // An object tracking the state of touchscreen on the delivery of gesture tap
-  // events to the renderer to filter taps immediately after a touchscreen fling
-  // canceling tap.
-  scoped_ptr<TouchscreenTapSuppressionController>
-      touchscreen_tap_suppression_controller_;
-
-  typedef std::deque<GestureEventWithLatencyInfo> GestureEventQueue;
-
-  // Queue of coalesced gesture events not yet sent to the renderer. If
-  // |ignore_next_ack_| is false, then the event at the front of the queue has
-  // been sent and is awaiting an ACK, and all other events have yet to be sent.
-  // If |ignore_next_ack_| is true, then the two events at the front of the
-  // queue have been sent, and the second is awaiting an ACK. All other events
-  // have yet to be sent.
-  GestureEventQueue coalesced_gesture_events_;
-
-  // Timer to release a previously deferred gesture event.
-  base::OneShotTimer<GestureEventFilter> debounce_deferring_timer_;
-
-  // Queue of events that have been deferred for debounce.
-  GestureEventQueue debouncing_deferral_queue_;
-
-  // Time window in which to debounce scroll/fling ends.
-  // TODO(rjkroege): Make this dynamically configurable.
-  int debounce_interval_time_ms_;
-
-  DISALLOW_COPY_AND_ASSIGN(GestureEventFilter);
-};
-
-}  // namespace content
-
-#endif  // CONTENT_BROWSER_RENDERER_HOST_INPUT_GESTURE_EVENT_FILTER_H_