Teach MainThreadEventQueue about touchmove throttling.

content/renderer/input/main_thread_event_queue.h

 // Copyright 2016 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_RENDERER_INPUT_MAIN_THREAD_EVENT_QUEUE_H_
 #define CONTENT_RENDERER_INPUT_MAIN_THREAD_EVENT_QUEUE_H_
 
 #include <deque>
 #include "base/feature_list.h"
 #include "content/common/content_export.h"
 #include "content/common/input/input_event_ack_state.h"
 #include "content/common/input/input_event_dispatch_type.h"
 #include "content/common/input/web_input_event_queue.h"
 #include "content/public/common/content_features.h"
 #include "content/renderer/input/scoped_web_input_event_with_latency_info.h"
 #include "third_party/WebKit/public/platform/WebInputEvent.h"
 #include "third_party/WebKit/public/platform/scheduler/renderer/renderer_scheduler.h"
 #include "ui/events/blink/web_input_event_traits.h"
 #include "ui/events/latency_info.h"
 
 namespace content {
 
 class EventWithDispatchType : public ScopedWebInputEventWithLatencyInfo {
  public:
   EventWithDispatchType(ui::WebScopedInputEvent event,
                         const ui::LatencyInfo& latency,
-                        InputEventDispatchType dispatch_type);
+                        InputEventDispatchType dispatch_type,
+                        bool originally_cancelable);
   ~EventWithDispatchType();
   void CoalesceWith(const EventWithDispatchType& other);
 
   const std::deque<uint32_t>& blockingCoalescedEventIds() const {
     return blocking_coalesced_event_ids_;
   }
   InputEventDispatchType dispatchType() const { return dispatch_type_; }
   base::TimeTicks creationTimestamp() const { return creation_timestamp_; }
   base::TimeTicks lastCoalescedTimestamp() const {
     return last_coalesced_timestamp_;
   }
 
   size_t coalescedCount() const {
     return non_blocking_coalesced_count_ + blocking_coalesced_event_ids_.size();
   }
 
+  bool originallyCancelable() const { return originally_cancelable_; }

[dtapuska, 2017/02/24 19:18:48]

Happy for another name. It's friday and I didn't have a better name :-)

[aelias_OOO_until_Jul13, 2017/02/24 20:19:51]

It doesn't seem that the additional state adds any information.  And because the
caller checks the inverse, it might be better to reverse the boolean.  So I'd
suggest:

bool originallyNonblocking() const { return dispatch_type_ == EventNonBlocking
|| dispatch_type_ == ListenersNonBlockingPassive; }

[dtapuska, 2017/02/24 20:23:35]

Not true. dispatch_type_ is whether an ACK needs to be returned. Not that it was
non-cancelable.

You can have a non-blocking event listener but still require it to return an
ACK.

[aelias_OOO_until_Jul13, 2017/02/24 21:01:14]

OK.  If I understand correctly, this is a problem with the name but not a bug in
the implementation I proposed.  I'd still prefer not storing a separate boolean:

bool originallyCancelable() const { return dispatch_type_ != EventNonBlocking
&& dispatch_type_ != ListenersNonBlockingPassive; }

[dtapuska, 2017/02/24 21:29:41]

These dispatch_types_ are of different enums. We really should rename the value
in the WebInputEvent

+
  private:
   InputEventDispatchType dispatch_type_;
 
   // Contains the unique touch event ids to be acked. If
   // the events are not TouchEvents the values will be 0. More importantly for
   // those cases the deque ends up containing how many additional ACKs
   // need to be sent.
   std::deque<uint32_t> blocking_coalesced_event_ids_;
   // Contains the number of non-blocking events coalesced.
   size_t non_blocking_coalesced_count_;
   base::TimeTicks creation_timestamp_;
   base::TimeTicks last_coalesced_timestamp_;
+
+  // Whether the received event was originally cancelable or not. The compositor
+  // input handler can change the event based on presence of event handlers so
+  // this is the state at which the renderer received the event from the
+  // browser.
+  bool originally_cancelable_;
 };
 
 class CONTENT_EXPORT MainThreadEventQueueClient {
  public:
   // Handle an |event| that was previously queued (possibly
   // coalesced with another event) to the |routing_id|'s
   // channel. Implementors must implement this callback.
   virtual void HandleEventOnMainThread(
       int routing_id,
       const blink::WebCoalescedInputEvent* event,
@@ skipping 51 matching lines @@
       MainThreadEventQueueClient* client,
       const scoped_refptr<base::SingleThreadTaskRunner>& main_task_runner,
       blink::scheduler::RendererScheduler* renderer_scheduler);
 
   // Called once the compositor has handled |event| and indicated that it is
   // a non-blocking event to be queued to the main thread.
   bool HandleEvent(ui::WebScopedInputEvent event,
                    const ui::LatencyInfo& latency,
                    InputEventDispatchType dispatch_type,
                    InputEventAckState ack_result);
-  void DispatchRafAlignedInput();
+  void DispatchRafAlignedInput(double frame_time_sec);
 
   // Call once the main thread has handled an outstanding |type| event
   // in flight.
   void EventHandled(blink::WebInputEvent::Type type,
                     blink::WebInputEventResult result,
                     InputEventAckState ack_result);
 
  private:
   friend class base::RefCountedThreadSafe<MainThreadEventQueue>;
   ~MainThreadEventQueue();
@@ skipping 22 matching lines @@
   bool handle_raf_aligned_touch_input_;
   bool handle_raf_aligned_mouse_input_;
 
   // Contains data to be shared between main thread and compositor thread.
   struct SharedState {
     SharedState();
     ~SharedState();
 
     WebInputEventQueue<EventWithDispatchType> events_;
     bool sent_main_frame_request_;
+    double last_async_touch_move_timestamp_;
   };
 
   // Lock used to serialize |shared_state_|.
   base::Lock shared_state_lock_;
   SharedState shared_state_;
 
   scoped_refptr<base::SingleThreadTaskRunner> main_task_runner_;
   blink::scheduler::RendererScheduler* renderer_scheduler_;
 
   DISALLOW_COPY_AND_ASSIGN(MainThreadEventQueue);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_INPUT_MAIN_THREAD_EVENT_QUEUE_H_