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

content/browser/renderer_host/input/base_gesture_event_filter.h

Index: content/browser/renderer_host/input/base_gesture_event_filter.h
diff --git a/content/browser/renderer_host/input/gesture_event_filter.h b/content/browser/renderer_host/input/base_gesture_event_filter.h
similarity index 58%
rename from content/browser/renderer_host/input/gesture_event_filter.h
rename to content/browser/renderer_host/input/base_gesture_event_filter.h
index 62949fbb2720457067343d52e5f57b423cff5d2b..bd08f60d07253dce30898206f4aa49a991c87cc6 100644
--- a/content/browser/renderer_host/input/gesture_event_filter.h
+++ b/content/browser/renderer_host/input/base_gesture_event_filter.h
@@ -2,14 +2,15 @@
 // 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_
+#ifndef CONTENT_BROWSER_RENDERER_HOST_INPUT_BASE_GESTURE_EVENT_FILTER_H_
+#define CONTENT_BROWSER_RENDERER_HOST_INPUT_BASE_GESTURE_EVENT_FILTER_H_
 
 #include <deque>
 
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/timer/timer.h"
+#include "content/browser/renderer_host/input/gesture_event_filter_client.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"
@@ -20,37 +21,14 @@ 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
+// 1. 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
+// 2. 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
@@ -59,58 +37,68 @@ class CONTENT_EXPORT GestureEventFilterClient {
 // sent together.
 // TODO(rjkroege): Possibly refactor into a filter chain:
 // http://crbug.com/148443.
-class CONTENT_EXPORT GestureEventFilter {
+class CONTENT_EXPORT BaseGestureEventFilter {
  public:
-  // Both |client| and |touchpad_client| must outlive the GestureEventFilter.
-  GestureEventFilter(GestureEventFilterClient* client,
-                     TouchpadTapSuppressionControllerClient* touchpad_client);
-  ~GestureEventFilter();
+  // |client| must outlive the BaseGestureEventFilter.
+  explicit BaseGestureEventFilter(GestureEventFilterClient* client);
+  virtual ~BaseGestureEventFilter();
 
   // Returns |true| if the caller should immediately forward the provided
   // |GestureEventWithLatencyInfo| argument to the renderer.
-  bool ShouldForward(const GestureEventWithLatencyInfo&);
+  virtual 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();
+  virtual void ProcessGestureAck(InputEventAckState ack_result,
+                                 WebKit::WebInputEvent::Type type,
+                                 const ui::LatencyInfo& latency);
 
   // 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;
-
+ protected:
   static bool ShouldIgnoreAckForGestureType(WebKit::WebInputEvent::Type type);
 
+  // Sub-filter for removing bounces from in-progress scrolls.
+  virtual bool ShouldForwardForBounceReduction(
+      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.
+  virtual bool ShouldForwardForCoalescing(
+      const GestureEventWithLatencyInfo& gesture_event);
+
+  virtual bool ShouldForwardScrollEndingEvent(
+      const GestureEventWithLatencyInfo& event);
+
   // 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.
+  // The receiver of all forwarded gesture events.
+  GestureEventFilterClient* client_;
+
+  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_;
+
+ private:
+  friend class MockRenderWidgetHost;
+  friend class GestureEventFilterTest;
 
   // 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;
@@ -120,28 +108,6 @@ class CONTENT_EXPORT GestureEventFilter {
   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.
@@ -164,13 +130,6 @@ class CONTENT_EXPORT GestureEventFilter {
   // 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_;
 
@@ -182,32 +141,8 @@ class CONTENT_EXPORT GestureEventFilter {
   // 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_;
+  base::OneShotTimer<BaseGestureEventFilter> debounce_deferring_timer_;
 
   // Queue of events that have been deferred for debounce.
   GestureEventQueue debouncing_deferral_queue_;
@@ -216,9 +151,9 @@ class CONTENT_EXPORT GestureEventFilter {
   // TODO(rjkroege): Make this dynamically configurable.
   int debounce_interval_time_ms_;
 
-  DISALLOW_COPY_AND_ASSIGN(GestureEventFilter);
+  DISALLOW_COPY_AND_ASSIGN(BaseGestureEventFilter);
 };
 
 }  // namespace content
 
-#endif  // CONTENT_BROWSER_RENDERER_HOST_INPUT_GESTURE_EVENT_FILTER_H_
+#endif  // CONTENT_BROWSER_RENDERER_HOST_INPUT_BASE_GESTURE_EVENT_FILTER_H_