Make the ContentGestureProvider a ui::FilteredGestureProvider

ui/events/gesture_detection/touch_disposition_gesture_filter.h

Index: ui/events/gesture_detection/touch_disposition_gesture_filter.h
diff --git a/ui/events/gesture_detection/touch_disposition_gesture_filter.h b/ui/events/gesture_detection/touch_disposition_gesture_filter.h
index 7721fe11c28009d90887990303b76cae219670a6..334d5caceddee3ad022b7797e9a2d108c7b0c5d3 100644
--- a/ui/events/gesture_detection/touch_disposition_gesture_filter.h
+++ b/ui/events/gesture_detection/touch_disposition_gesture_filter.h
@@ -7,6 +7,7 @@
 
 #include <queue>
 
+#include "ui/events/event_constants.h"
 #include "ui/events/gesture_detection/bitset_32.h"
 #include "ui/events/gesture_detection/gesture_detection_export.h"
 #include "ui/events/gesture_detection/gesture_event_data_packet.h"
@@ -41,64 +42,42 @@ class GESTURE_DETECTION_EXPORT TouchDispositionGestureFilter {
   };
   PacketResult OnGesturePacket(const GestureEventDataPacket& packet);
 
-  // TODO(jdduke): Consider adoption of ui::EventResult.
-  enum TouchEventAck {
-    CONSUMED,
-    NOT_CONSUMED,
-    NO_CONSUMER_EXISTS
-  };
   // To be called upon receipt of *all* touch event acks.
-  void OnTouchEventAck(TouchEventAck ack_result);
+  void OnTouchEventAck(bool event_consumed);
 
   // Whether there are any active gesture sequences still queued in the filter.
   bool IsEmpty() const;
 
  private:
-  // Utility class for tracking gesture events and dispositions for a single
-  // gesture sequence. A single sequence corresponds to all gestures created
+  // A single GestureSequence corresponds to all gestures created
   // between the first finger down and the last finger up, including gestures
   // generated by timeouts from a statinoary finger.
-  class GestureSequence {
+  typedef std::queue<GestureEventDataPacket> GestureSequence;
+
+  // Utility class for maintaining the touch and gesture handling state for the
+  // current gesture sequence.
+  class GestureHandlingState {
    public:
-    struct GestureHandlingState {
-      GestureHandlingState();
-      // True iff the sequence has had at least one touch acked.
-      bool seen_ack;
-      // True iff the sequence has had any touch down event consumed.
-      bool start_consumed;
-      // True iff the first ack received for this sequence reported that no
-      // consumer exists.
-      bool no_consumer;
-    };
-
-    GestureSequence();
-    ~GestureSequence();
-
-    void Push(const GestureEventDataPacket& packet);
-    void Pop();
-    const GestureEventDataPacket& Front() const;
-    void UpdateState(GestureEventDataPacket::GestureSource gesture_source,
-                     TouchEventAck ack_state);
-    bool IsEmpty() const;
-    const GestureHandlingState& state() const { return state_; };
+    GestureHandlingState();
 
-   private:
-    std::queue<GestureEventDataPacket> packets_;
-    GestureHandlingState state_;
-  };
-  bool IsGesturePrevented(GestureEventType type,
-                          TouchEventAck current,
-                          const GestureSequence::GestureHandlingState& state)
-      const;
+    // To be called on each touch event ack.
+    void OnTouchEventAck(bool event_consumed, bool is_touch_start_event);
 
-  void UpdateAndDispatchPackets(GestureSequence* sequence,
-                                TouchEventAck ack_result);
+    // Returns true iff the gesture should be dropped.
+    bool Filter(GestureEventType type);
 
-  void FilterAndSendPacket(
-      const GestureEventDataPacket& packet,
-      const GestureSequence::GestureHandlingState& sequence_state,
-      TouchEventAck ack_state);
+   private:
+    // True iff the sequence has had any touch down event consumed.
+    bool start_touch_consumed_;
+    // True iff the most recently ack'ed touch event was consumed.
+    bool current_touch_consumed_;
+    // If the previous gesture of a given type was dropped instead of being
+    // dispatched, its type will occur in this set. Cleared when a new touch

[tdresser, 2014/03/03 19:44:32]

Update comment. (No longer cleared)

[jdduke (slow), 2014/03/03 22:33:17]

Done.

+    // sequence begins to be acked.
+    BitSet32 last_gesture_of_type_dropped_;

[tdresser, 2014/03/03 19:44:32]

Why does the last_gesture_of_type_dropped_ need to be per sequence?

[jdduke (slow), 2014/03/03 22:33:17]

Are you thinking of the double-tap case? I don't see any harm in resetting it
along with the other state tracking bits when a new touch sequence becomes
current.

[tdresser, 2014/03/04 13:48:35]

You're right, this is fine. I was forgetting that BitSet32 is super light.

+  };
 
+  void FilterAndSendPacket(const GestureEventDataPacket& packet);
   void SendGesture(const GestureEventData& gesture);
   void CancelTapIfNecessary();
   void CancelFlingIfNecessary();
@@ -109,10 +88,7 @@ class GESTURE_DETECTION_EXPORT TouchDispositionGestureFilter {
   TouchDispositionGestureFilterClient* client_;
   std::queue<GestureSequence> sequences_;
 
-  // If the previous gesture of a given type was dropped instead of being
-  // dispatched, its type will occur in this set. Cleared when a new touch
-  // sequence begins to be acked.
-  BitSet32 last_event_of_type_dropped_;
+  GestureHandlingState state_;
 
   // Bookkeeping for inserting synthetic Gesture{Tap,Fling}Cancel events
   // when necessary, e.g., GestureTapCancel when scrolling begins, or