components/scheduler/renderer/user_model.h

   1 // Copyright 2015 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef COMPONENTS_SCHEDULER_RENDERER_USER_MODEL_H_
   6 #define COMPONENTS_SCHEDULER_RENDERER_USER_MODEL_H_
   7
   8 #include "base/macros.h"
   9 #include "base/trace_event/trace_event.h"
  10 #include "base/trace_event/trace_event_argument.h"
  11 #include "components/scheduler/renderer/renderer_scheduler.h"
  12 #include "components/scheduler/scheduler_export.h"
  13 #include "third_party/WebKit/public/web/WebInputEvent.h"
  14
  15 namespace scheduler {
  16
  17 class SCHEDULER_EXPORT UserModel {
  18  public:
  19   UserModel();
  20   ~UserModel();
  21
  22   // Tells us that the system started processing an input event. Must be paired
  23   // with a call to DidFinishProcessingInputEvent.
  24   void DidStartProcessingInputEvent(blink::WebInputEvent::Type type,
  25                                     const base::TimeTicks now);
  26
  27   // Tells us that the system finished processing an input event.
  28   void DidFinishProcessingInputEvent(const base::TimeTicks now);
  29
  30   // Returns the estimated amount of time left in the current user gesture, to a
  31   // maximum of |kGestureEstimationLimitMillis|.  After that time has elapased
  32   // this function should be called again.
  33   base::TimeDelta TimeLeftInUserGesture(base::TimeTicks now) const;
  34
  35   // Tries to guess if a user gesture is expected soon. Currently this is
  36   // very simple, but one day I hope to do something more sophisticated here.
  37   // The prediction may change after |prediction_valid_duration| has elapsed.
  38   bool IsGestureExpectedSoon(RendererScheduler::UseCase use_case,
  39                              const base::TimeTicks now,
  40                              base::TimeDelta* prediction_valid_duration) const;
  41
  42   void AsValueInto(base::trace_event::TracedValue* state) const;
  43
  44   // The time we should stay in a priority-escalated mode after an input event.
  45   static const int kGestureEstimationLimitMillis = 100;
  46
  47   // TODO(alexclarke): Get a real number on actual data.
  48   static const int kMinimumTypicalScrollDurationMillis = 500;
  49
  50   // We consider further gesture start events to be likely if the user has
  51   // interacted with the device in the past two seconds.
  52   // TODO(alexclarke): Get a real number based on actual data.
  53   static const int kExpectSubsequentGestureMillis = 2000;
  54
  55   // Clears input signals.
  56   void Reset();
  57
  58  private:
  59   int pending_input_event_count_;
  60   base::TimeTicks last_input_signal_time_;
  61   base::TimeTicks last_gesture_start_time_;
  62   base::TimeTicks last_continuous_gesture_time_;  // Doesn't include Taps.
  63
  64   DISALLOW_COPY_AND_ASSIGN(UserModel);
  65 };
  66
  67 }  // namespace scheduler
  68
  69 #endif  // COMPONENTS_SCHEDULER_RENDERER_USER_MODEL_H_